Undercover Investigations

Below is a brief summary of our evaluation of undercover investigations. See our full evaluation for more details on how it performed on our criteria.


Animal advocacy organizations use undercover1 investigations, sometimes just referred to as investigations, to document animal abuse and raise awareness of various forms of suffering and injustice against animals. This increased awareness is expected to result in various outcomes that benefit animals, including influencing company policies, laws, and consumption choices. We focus our research on investigations of animal agriculture,2 but this intervention is also used to document animal abuse in other areas, such as laboratory research that involves live animals3 and the breeding of companion animals.4 We believe that undercover investigations have had significant direct effects in reducing farmed animal suffering through corporate policy change. We think they also have major effects, in expectation,5 on consumption choices and some long-term outcomes such as increasing the likelihood of future corporate policy change, although the size of long-term effects is much more uncertain. While there's a chance that some undercover investigations could have bad long-term outcomes, we think that risk is relatively small.

What are undercover investigations?

We use the term “undercover investigation” to refer to any project where activists obtain documentation (e.g. photos and videos) of the treatment of animals without the explicit cooperation of the people or organizations using the animals. We focus primarily on investigations of farms and other animal agriculture facilities. This documentation is usually shared with the public through mainstream news and social media.6 Although the evidence obtained is sometimes used to press charges, the documented abuses are often legal and standard industry practice.7 Organizations present the evidence from these investigations alongside messages that advocate for the end of animal agriculture, advocate for less suffering of farmed animals (but not opposing animal agriculture itself), or a blend of the two.

Investigations are often connected to other forms of advocacy. The documentation and public outrage resulting from the investigation is often used by the investigating organization to pressure the company supplied by the facilities being investigated to improve its animal welfare policies.8 The documentation is also sometimes used in grassroots and online outreach intended to inspire consumers to reduce or eliminate their consumption of animal products.9

What are their strengths?

In the best-case scenario, undercover investigations can lead to immediate changes through corporate or legal policy change and consumers reducing their consumption of animal products, as well as contribute to long-term outcomes by growing the animal advocacy movement and increasing public concern for farmed animal issues.

Investigations seem to gather a significant amount of attention in the news and on social media.10 There is also clear evidence that they have led to corporate policy change.11 We are much more uncertain what effects they have on consumer choices and long-term change, although we expect both are fairly promising.

We are also quite uncertain about what factors make an investigation most effective. Some factors, like whether an individual worker is criminally charged or whether the focus of the investigation is on blatant abuse like punching and kicking animals, might increase the amount of attention an investigation receives, but also might reduce the impact of the publicity because (i) this abuse seems more easily dismissed as “one bad farm” or “one bad worker,” and (ii) the issue being highlighted constitutes a smaller portion of the the total suffering farmed animals endure compared to practices like extreme confinement and chronic health issues.12, 13

In addition to focusing on the most severe forms of suffering, we think that investigations can be more effective by focusing on individual stories. This can involve combining footage of various facilities to show the life story of the farmed animals. It can also involve highlighting the work of a specific investigator, especially when they discuss how the investigation affected them personally. We generally believe storytelling is an effective way to promote empathy and connect people with farmed animal issues.14

It seems like some factors likely increase the impact of investigations in specific situations. For example, when a certain unethical practice, such as confining hens in battery cages, is being critiqued in popular media, investigations that highlight this issue could synergize with existing pressure to change policies or gain additional attention.15

What are their weaknesses?

Although we have seen substantial impact from investigations in terms of media coverage and corporate policy change, there’s less evidence for their potential impact on consumer choices and long-term outcomes. One concern, mentioned above, is that some investigations might give the impression that the issues with the animal agriculture industry are limited to a few abusive workers. Although we recognize this concern, we think that current media coverage indicates that the public recognizes more pervasive issues, such as the confinement of animals in battery cages and gestation crates.16

The undercover investigations that achieve the most coverage in the U.S. are those that involve investigators gaining employment at animal agriculture facilities.17 These investigations are quite expensive compared to strategies popular in other countries like visiting the facility at night and placing hidden cameras to document abuse.18 Still, even employment-based investigations seem to be a cost-effective way of capturing media coverage.19

It appears that, at least in the U.S., undercover investigations have diminishing marginal returns in their ability to capture media coverage after a certain point. Mercy For Animals capped the number of investigations released in 2015 for this reason,20 and are working on expansion into other countries where saturation is less of a concern.21 There are many countries where investigations have not become very popular, and as long as one believes work in these countries is not much less effective, this means additional funding likely has similar effects as existing funding in undercover investigations. Additional funding might have greater effects in some countries due to lower costs.

There’s a plausible concern that this saturation suggests all future investigations are less effective, rather than just investigations beyond the current rate. We aren’t very concerned about this because media outlets appear to be at least as interested in covering investigations as they used to be as long as there are not too many being released around the same time, and further investigations make the average reader/viewer more likely to realize that the issues are systemic across the animal agriculture industry.

Overall, we think the weaknesses of undercover investigations are limited.

What about long term effects?

Possible Positive Effects

The long term effects of undercover investigations are quite unclear, and we have little evidence available here beyond speculative reasoning.

Similarly to corporate outreach, we think investigations can promote discussion and concern for the treatment of farmed animals. In the long term, this can increase the chances of success for other advocacy efforts, such as leafleting and ads, corporate policy change, and legal change. The current perception in the U.S. that farmed animals are frequently mistreated for commercial gain,22 especially through extreme confinement practices, might be the result, at least in part, of the many undercover investigations released over the past several years.23 The outreach methods like leafleting and online ads that use undercover investigations might also be a significant factor in this change.

Possible Negative Effects

As with possible positive long term effects, we have much uncertainty about the possible negative long term effects.

The footage used in undercover investigation videos could make people depersonalize the individual animals affected, especially if the rhetoric of the video is abstract and generalized rather than speaking of the animals as individuals.24 It’s possible that incorporating “happy” footage of animals, like that from farmed animal sanctuaries, could reduce this effect if it exists.

Many investigations focus on blatant abuse by individual workers, such as punching and kicking the animals.25 They also tend to target a specific farm.26 This could risk making people think the issues of animal agriculture are localized or exist at only a few “bad apple” farms. We think this concern is reduced when viewing undercover investigations in aggregate. Given how many have come out, and that advocate rhetoric emphasizes the systemic nature of the abuse, we don’t think this is a significant concern.

Investigations frequently involve deceit, such as working at the farm while wearing hidden cameras. Some investigations that don’t involve deceit involve visiting farms without the permission of the facility’s owners.27 Either of these approaches could lead to a negative view of animal advocates if they are seen as liars or criminals. On the other hand, they could also make advocates seem brave or make the cause seem more important since advocates are willing to go to such lengths to help the animals, which seems to be more common in public discussion of investigations to date.28


Overall, we think investigations fit well into long term animal advocacy strategy. It seems more likely than not that investigations increase concern for farmed animals, and that outcome seems very promising for building a better world for animals. There are plausible concerns that some investigations could negatively affect the way people perceive animal abuse, such as by suggesting that it is a localized concern that can be easily resolved. Like with other animal advocacy interventions, we are much more uncertain about the long-term effects than the short-term effects. We would tentatively conclude that the long-term effects of investigations seem more promising than other interventions like leafleting and corporate outreach, but we put limited weight on this consideration in our overall understanding of how effective or ineffective any intervention is.

Do we recommend it? Why or why not?

We recommend undercover investigations in most instances when done by experienced organizations, although we are concerned about saturation in the U.S. that could reduce the effectiveness of investigations beyond the current level, and the potential for investigations that are conducted poorly to reduce the overall reputation of animal advocates. We think that more research is needed on what makes some investigations more impactful than others, but tentatively, we consider thoughtful messaging, such as emphasizing that abuse is rampant throughout the industry and highlighting the stories of individual animals, as important. Additionally, undercover investigations seem particularly effective when coupled with other advocacy strategies, such as protests and corporate outreach, especially if they provide public pressure for a specific campaign, such eliminating battery cages.

What are characteristics of a strong undercover investigation?

  • Coverage of the investigation reaches a wide audience, usually by being featured in a major news outlet and promoted on social media. This increases the number of people who may change their consumption as a result of the investigation, participate in activism, or help animals in other ways. It also increases the credibility of the investigation, which can make individuals and institutions, such as animal agriculture companies, take the investigation more seriously. We are fairly uncertain about what increases coverage of an investigation, but some promising factors include connections from the farm being investigated to well-known companies and the existing media contacts of the organization conducting the investigation.
  • The investigation is conducted with careful consideration for how it will be perceived by the general public, limiting the risk of harm from advocates being seen as inappropriately deceitful, criminal, or having other negative features and the risk of investigators being charged with a crime, including associated legal fees. This is especially important because it could affect the perception of investigation groups in general.
  • The investigation is conducted with a thoughtful understanding of the current landscape of animal advocacy, including which practices or companies are currently under heightened scrutiny. By incorporating that focus, such as investigating a battery cage facility while battery cage bans are being discussed in the national media, an investigation can both gain increased attention and make other efforts more likely to succeed, such as legal and corporate reform.
  • The messaging used when the investigators present their documentation is optimized to effect change, such as by highlighting individual animals and systemic abuse. Highlighting the fact that the mistreatment of animals is an institutional issue, rather than a personal or localized issue, might do more to inspire positive action such as dietary change and activism. A systemic focus also aligns investigating organizations with other groups who advocate on behalf of workers in the animal agriculture industry. These workers often suffer from physical hazards, difficulty in earning a living wage, and other issues.29
  • The investigation is conducted by an organization with prior experience in this area, or the leaders of the project have discussed possible strategies with an experienced organization. There are many organizations with strong records in undercover investigations, and advocates should use their experience to inform future campaigns. Some organizations that have had success with undercover investigations are Mercy For Animals, Animal Equality, Compassion Over Killing, Direct Action Everywhere, The Humane Society of the United States, and People for the Ethical Treatment of Animals. Each of these groups uses somewhat different tactics.

How strong is the evidence about the efficiency of undercover investigations?

The primary immediate effects of undercover investigations ― corporate policy change and media coverage ― are directly observable, although the extent to which policy changes are attributable to an investigation as opposed to corporate outreach is unclear.

The other effects of undercover investigations, such as reductions in consumption of animal products, have less robust evidence. The most scientific piece of evidence we know of is an economics study that found, “Increasing media attention to animal welfare issues triggers consumers to purchase less meat rather than reallocate expenditures across competing meats,” based on an analysis of national consumption data and numbers of new stories between 1999 and 2008.30 Our report on this study, and a similar study on media attention and demand for eggs, found them to be inconclusive.31 We will also consider ways that we can conduct similar analyses of our own on the relationship between media coverage and consumer purchases.

Given the limited evidence on the effects of undercover investigations on dietary change and other indirect outcomes, we are uncertain but quite optimistic about the total impact of this intervention.


Conversation with Wayne Hsiang
Conversation with Carter Dillard
Conversation with Matt Rice
Private communication with a representative of a charity that conducts numerous investigations outside the United States.

  1. We primarily focus on investigations that involve going “undercover,” meaning without the facility owner’s explicit consent to document the facilities and use that documentation to spread awareness of the problems involved. Some investigations, but not many, do involve explicit cooperation, such as when a chicken farmer working for Perdue Farms cooperated with Compassion in World Farming to document what the farmer saw as inappropriate farming practices. See McKenna, M. (February 19, 2015). A Factory Farmer Strikes Back at the Company He Works for. Wired.

    Our claims in this review apply similarly to different types of investigations, including employment-based, open rescues, and cooperative. We have noted where our beliefs differ depending on the type of investigation. 

  2. For more information on our focus on farmed animals, see our cause prioritization page. 

  3. HSUS is one organization that conducts undercover investigations of live animal research facilities.

    “A nine-month undercover investigation by The Humane Society of the United States (HSUS) has pulled back the curtain on the secretive, federally-funded New Iberia Research Center (NIRC) in Louisiana, revealing routine and unlawful mistreatment of hundreds of chimpanzees and other primates.” - (March 4, 2009). Undercover Investigation Reveals Cruelty to Chimps at Research Lab. HSUS. 

  4. PETA is one organization that conducts undercover investigations of “puppy mills.”

    “A PETA investigator worked for months at Nielsen Farms, a puppy mill in Kansas. The investigator’s job was to feed, water, and clean up after hundreds of dogs condemned to cramped wire enclosures.” - Puppy Mill Prison. PETA. 

  5. By “in expectation,” we mean “in terms of expected value,” which is the product of the likelihood of the effect and the magnitude of the effect if it occurs. For example, we would say taking a lottery where you have a 10% likelihood of earning a million dollars has a major effect on your total income, in expectation, even though the most likely outcome is that you will not win the lottery. 

  6. “MFA also reaches out to mainstream media outlets that might be interested in covering the investigation.

    Mainstream media is not the only way that MFA distributes their work; they also use social media.” - Conversation with Matt Rice (February 9, 2015). 

  7. “Matt, MFA’s legal team, and independent animal welfare experts then review relevant portions of the footage and evaluate whether what it shows is criminal abuse or standard industry practice (which is also abusive). When criminal abuse is identified, Matt works with MFA’s legal team to draft formal complaints and get them to appropriate law enforcement agencies.” - Conversation with Matt Rice (February 9, 2015). 

  8. “MFA’s investigation team also works to identify all the links in the facilities supply chain, from the farm to the point of sale for consumers, so MFA can work with companies in the supply chain to make animal welfare policy changes.” - Conversation with Matt Rice (February 9, 2015). 

  9. For example, the meatvideo.com website used by MFA currently shows the video, “What Cody Saw Will Change Your Life,” which features the story of one of its investigators and some footage of investigations. (Accessed December 31st, 2015.)  

  10. It seems most media coverage of the suffering of animals in animal agriculture is in response to undercover investigations. The other common topic is corporate policy change, such as switching to cage-free eggs. Other forms of activism like leafleting and protests seem to get less media coverage relative to the amount of resources put into them, although we have not done a systematic analysis of the differences.

    For example, Animal Equality estimates that their investigations have earned 182 million media views in 2015 and 312 million in 2014. 

  11. For example, “The investigation at Wiese Brothers Farms led to one of their largest corporate outreach victories. This was a dairy farm that they connected to DiGiorno Pizza, which is owned by Nestle, the largest food company in the world. Nestle got such a large media and public response that they decided to work with MFA to implement an animal welfare policy, and the policy they implemented is probably the most comprehensive animal welfare policy ever implemented by a company. They announced a policy change in 2014 that will apply to every farm that supplies them, in 90 countries.” - Conversation with Matt Rice (February 9, 2015). 

  12. One example of an investigation that focused on blatant worker abuse was a recent video released of a Perdue chicken supplier. News coverage of this investigation mostly focused on the individual worker’s actions, such as this piece, “Man arrested after undercover video reveals alleged abuse at Perdue chicken supplier,” in the Washington Post. The quotes from animal advocates in the piece did refer to the systemic nature of abuse in the industry, which we see as increasing the impact of the coverage. 

  13. Although we do not have a formal write-up on which abuses of farmed animals cause the most suffering, and such judgments are necessarily subjective, we think we can make reasonable estimations based on the length the suffering is endured and the severity at each moment. We expect worker abuse, such as punching and kicking, is endured for a much shorter period of time per animal than confinement and health issues, and does not have a proportionally larger severity. We think most animal advocates familiar with these issues would agree with this assessment. 

  14. See some of the resources in the Social Psychology section of our Research Library, including "’If I look at the mass I will never act’": Psychic numbing and genocide” and “Explaining the ‘Identifiable Victim Effect.’” 

  15. An example of this strategy was a 2008 investigation of a California egg farm by Mercy For Animals, which was released shortly before California voted on Prop 2, a ballot proposition that prohibits certain kinds of extreme confinement of farmed animals. 

  16. In 2015, there was substantial media coverage of battery cages, which frequently referred to undercover investigations and addressed the systemic nature of the issue, such as, “Free the Hens, Costco!” in the New York Times. “Even after an undercover investigation recently documented a Costco egg supplier locking birds in cages with the mummified corpses of their dead cage mates, Costco responded that the supplier was ‘behaving appropriately.’” 

  17. The only U.S. group we know of currently doing non-employment-based investigations is Direct Action Everywhere (DXE), which released their first investigations in 2015. The two investigations they have released seem to have received less media coverage than other investigations, although this could change as DXE grows.

    Note, the following quote comes from a conversation that took place before the second investigation DXE released, “DXE has had 50 press appearances in 2015 so far, and they expect to get 3-5 per month throughout the year. They estimate that 50-100k people were exposed to animal rights as a result of each of these press appearances. In addition, they place a lot of emphasis on social networks; they had over 50k unique views on their video, and they estimate 5 million people were exposed to their work through social media in the weeks after the initial release, including shared demonstrations and press coverage. This estimate is approximate, since some data is hard to collect with their decentralized model.” - Conversation with Wayne Hsiung (March 13, 2015).

    Mercy For Animals is the group that seems to conduct the most investigations in the United States and uses an employment-based strategy. From January to August 2015, they recorded 7,069 media pieces about their work with an estimated billions of people reached with six investigations.

    We would note that we have large uncertainty about whether employment-based investigations are actually better at producing media coverage, especially given the small sample size available and confounding variables at play, such as the differing ages and sizes of these organizations. We are not comfortable making a claim in either direction for this effect. 

  18. Private communication with a representative of a charity that conducts numerous investigations outside the United States. 

  19. See the cost-effectiveness estimates in our reviews of Mercy For Animals

  20. “This number is purposefully lower than last year because they were concerned too many investigations could reduce the amount of attention each new one gets in the media.” - Conversation with Nick Cooney (September 2, 2015). 

  21. “They now have a full-time investigator in India, gathering footage for them. The first release in India is going to be different than the ones in North America. They also have contracted an investigation firm in China to work in each of the main animal agriculture industries, such as eggs, poultry, pork. In Mexico, MFA has two investigators ready to start working who are Mexican citizens. MFA is finishing legal due diligence to be sure they conduct their investigations within the bounds of state and federal laws.


    These investigations are especially exciting because there haven’t been many investigations in these countries. This means they are more likely to grab substantial media attention, spark public outrage, and prompt corporate and policy changes.” - Conversation with Nick Cooney (September 2, 2015).

  22. We think most people who work on farmed animal advocacy would agree with this claim based on their personal experiences interacting with the public. In general, we haven’t found very convincing survey evidence for or against the claim, but there is one survey that found “A total of 64% of survey respondents agree with the statement, ‘farmers and food companies put their own profits ahead of treating farmed animal humanely.’” Lusk, J, Norwood, B.F., Prickett, R. (August 17, 2007). Consumer Preferences for Farm Animal Welfare: Results of a Nationwide Telephone Survey. Oklahoma State University. 

  23. Although we haven't performed a full analysis, it appears that public awareness of poor conditions for farmed animals has increased over the last 10-20 years. For instance, we think there has been more discussion of these issues in the media and through documentaries, and there has been more public reaction through seeking out "humane" alternatives and supporting legal and corporate policies that restrict certain practices. These changes correspond to the growth of undercover investigations as a tactic, and it's clear how undercover investigations could lead to increased public awareness and that farmers and corporations react to them as if they do. 

  24. It seems plausible that if identifiable victims make a problem more personal and personalize the victims, then discussing the issue without identifiable victims could have the opposite effect. However, we have not seen substantial evidence for this effect and we consider it only as a possibility rather than a likely downside. 

  25. One example of an investigation that focused on blatant worker abuse was a recent video released of a Perdue chicken supplier. News coverage of this investigation mostly focused on the individual worker’s actions, such as this piece, “Man arrested after undercover video reveals alleged abuse at Perdue chicken supplier,” in the Washington Post. The quotes from animal advocates in the piece did refer to the systemic nature of abuse in the industry, which we see as increasing the impact of the coverage. 

  26. Scanning through lists of undercover investigations, such as this one, or lists of news articles covering investigations, we see that most focus on the specific farm involved, often naming them in the headline or mentioning that it was a farm, rather than the industry as a whole, where the abuse occurred. 

  27. Direct Action Everywhere conducts this sort of investigation in the United States. When the activists are open about their identities and activities, these are referred to as “open investigations” or “open rescues” (if at least one animal is rescued from the farm by the activists). 

  28. One of the largest examples of this framing has been the media and public reaction to “ag gag” laws that have been introducing in state legislatures to prevent undercover investigations from happening. Even media outlets that tend to be less opinionated have still condemned these laws and talked about the importance of undercover investigation work, such as in this interview on CNN Money in June 2015. 

  29. For more information on the harms suffered by workers in the animal agriculture industry, see this summary by the Food Empowerment Project. 

  30. “As a whole, media attention to animal welfare has significant, negative effects on U.S. meat demand; Direct effects of media attention are primarily associated with pork and poultry demand; Increasing media attention to animal welfare issues triggers consumers to purchase less meat rather than reallocate expenditures across competing meats.” - Tonsor, Glynn T., Olynk, Nicole J. (September 2010). U.S. Meat Demand: The Influence of Animal Welfare Media Coverage. Kansas State University. 

  31. Regarding the egg study: "With moderately more certainty, we can conclude that Prop 2 media coverage resulted in slight increases in demand for cage-free and organic eggs, and a slight decrease in demand for conventional eggs, but did not cause a decrease in demand for eggs in general."

    Regarding the meat study: "While this is consistent with the hypothesis that media coverage of animal welfare causes a decrease in demand for meat, their evidence is not sufficient to substantially increase our confidence in this hypothesis." - Models of Media Influence on Demand for Animal Products