Cynthia von Schlichten

Measuring Their Worth: Looking Beyond Sentience to Grant Non-Human Animal Protections

This piece was written for Lewis & Clark’s Emerging Topics in Animal Law course. All views expressed are those of the author.

By Cynthia von Schlichten


Welcome to the 20th Century: Non-Human Animals Are Sentient

Throughout history, a non-human animal (“NHA”) has been categorized as property in legal systems across civilized societies. This has historically meant that an animal only had worth that one could liken to that of a piece of clothing, and that their value was contingent upon ownership by a human being. For hundreds of years, there was no real legal or scientific consideration as to whether or not NHAs were sentient. The idea that NHAs were non-sentient came into popularity in the 17th century by philosopher, René Descartes,[1] and this idea persisted with gusto until the second half of the 20th century. I believe that the reluctance to explore the undeniable conclusion that NHAs are sentient was likely secondary to a fear that opening that Pandora’s box could lead to a complete reevaluation of how we use NHAs to meet our needs and desires in everyday life and humankind was just not ready to go there.

In 1976, France chose to connect the recognition of NHA sentience to a requirement that NHAs must be kept in conditions that met the biological requirements of a particular species.[2] In 2009, the European Union (“EU”) enacted the Lisbon Treaty, which was an amendment to the EU’s Treaty on the Functioning of the European Union and stated that “the Union and the Member States shall, since animals are sentient beings, pay full regard to the welfare requirements of animals…”[3] In 2015, France went even further by amending its civil code to change the legal status of animals from “moveable property” to “living beings gifted [with] sentience.”[4] Today, more than 20 countries officially recognize NHAs as sentient beings.[5]

But what does this new classification for a NHA really mean from a legal perspective? Some jurisdictions that recognize sentience in NHAs may still classify them as property, but this recognition has, in some cases, given NHAs increased protections. For instance, the EU has improved standards for certain NHAs based on the recognition of sentience. This may cause one to conclude that conversations around NHA sentience are generally a positive development in the world of animal rights/protection. However, my fear is that by making sentience, as we currently understand it, a primary qualifier for expanding the likelihood of NHAs being afforded additional legal protections, we stand to leave countless species without any protections at all.

In this blog, I will explore how sentience is determined from a scientific perspective and will review examples of how laws that protect NHAs are evolving under the purview that NHAs are sentient. Finally, I will address the flaws in thinking that sentience should be a primary determination for increased protections.

Sentience Defined

First, it is logical to ask, what is sentience? The basic definition is relatively universal. Merriam Webster defines a sentient being as, “one who perceives and responds to sensations of whatever kind-sight, hearing, touch, taste, or smell.”[6] Some define sentience as the ability to feel, perceive, or experience subjectively (emphasis added).[7] The Sentience Institute defines it as, “the capacity to have positive and negative experiences, usually thought of as happiness and suffering.” [8] Some definitions also include self-awareness as an indicator of sentience.[9]

The Science in Sentience

Regardless of which definition is used, how do scientists determine whether or not a species is sentient? There are three basic criteria, each involving specific considerations, which are 1.) behavioral; 2.) evolutionary; and 3.) physiological.[10] Each will be briefly addressed here.

From a behavioral standpoint, observing certain behaviors can help determine if a NHA is having a positive or negative experience. It is important to consider not only how a NHA reacts in a certain situation, but how they act, in general. That “general” behavior can lead to a conclusion that an animal is sentient, even absent clear evidence of reactionary behavior. This is because any evidence that a NHA is making decisions based on its desire for survival, such as running away from predators, seeking out food, etc. suggests the presence of sentience.

From an evolutionary standpoint, scientists assert that consciousness is required, at least in part, for a species to survive. More specifically, scientists propose two ways in which evolutionary considerations suggest the presence of sentience. One, is considering a NHA’s reaction to its surroundings or circumstances with the end result being sustainability of that species. Two, is the relationship or connection to species that are similar to each other, such as humans and primates. If one is considered sentient, the other is likely so.

Finally, scientists consider sentience from the physiological standpoint. It is believed that a central nervous system is indicative of sentience, regardless of the complexity of that system. Another physiological point is the presence of analgesics in the NHA’s system; the belief being that if a NHA inherently creates a secretion for the express purpose of minimizing pain, that NHA must be sentient.

Legal Impact of Sentience

Scientists have established their formula for determining sentience, but what is the legal significance of that determination when creating laws to protect NHAs?

As discussed, many jurisdictions now define some NHAs as sentient creatures and this can have a significant impact on our decisions that affect their welfare. For instance and as noted previously, the EU legally recognizes NHAs as sentient beings in its treaties and as a result, Member States and the EU as a whole must consider and address animal welfare when implementing and imposing welfare requirements for the treatment of farmed animals. As a result, EU laws that protect farmed animals are leading the animal protection movement in this regard. Notably, EU laws are immeasurably better than the laws in the United States, which fails to recognize sentience in NHAs at all at a federal level. Surely there is a correlation between these two realities.

Is Science Failproof Regarding Sentience?

From this layperson’s perspective, the formula noted above for determining sentience appears thoughtful and thorough. If scientists just follow this format, no sentient NHA will be left behind, and if sentience becomes a primary benchmark for the justification of increased NHA protection, all sentient NHAs will be included. Unfortunately, I am not convinced of this. Remember that at one point in time, the best scientists in the world were positive the Earth was flat.

Fishes Are Sentient Just as the Earth Is Round

Fishes are a prime example of why using sentience as a main qualifier for whether or not a NHA should be afforded legal protections beyond their traditional property status is a flawed strategy. Until just a few years ago, scientists were convinced that fishes did not feel pain.[11]

Fast forward to the last few years, and now scientists by and large enthusiastically concede that fishes are sentient creatures. Extensive scientific evidence indicates that fishes are capable of emotions such as pain, fear and psychological stress.[12] Fishes have been determined to access consciousness, which means they have the ability to introspectively think about a mental state or information, as well as phenomenal consciousness, which is centered around self-awareness. Fishes have also been shown to have emotional responses to pain.[13]

When looking at the overwhelming evidence that fishes are sentient, it is hard to imagine that 1.) there was a time when the idea was completely rejected by scientists and; 2.) why much of the world (including the legal one) continues ignore this reality that seems so obvious and unequivocal.

What took science so long to finally acknowledge that fishes are sentient creatures? I think a main reason is that all of this talk about sentience and NHAs is approached through an anthropocentric lens. How do we experience happiness or pain? Additionally, even if humans can start to concede to the possibility of NHAs being sentient, how will that realization impact us? And not just terrestrial NHAs that share many similar characteristics with humans, but what about NHAs that communicate in a way we don’t understand, live in water, and have some notable anatomical differences from humans? It seems to be a tall order for human beings to accept this and despite the overwhelming evidence of fish sentience, the legal world has yet to meaningfully sign on.

Approximately 2.7 trillion fishes are killed by humans each year through fishing, aquaculture, and pollution.[14] Currently, legislation addressing the welfare of fishes is extremely limited in most countries.[15] One could argue that this is largely because until very recently, fishes were dismissed as non-sentient creatures. Will this new sentience classification have a meaningful impact on welfare laws for fishes? Not yet.

All Sentience Is Not Created Equal

Clearly, a sentience classification is not a “one size fits all” distinction that automatically affords a NHA additional protections, despite it being stated as a primary factor for awarding greater protections. In reality, the stated reliance on sentience seems to be more a tool for keeping a species out of the conversation of additional protections, rather than a path to granting additional protections, as significant inconsistencies lie in how one sentient NHA is treated compared to another. For instance, NHAs who are classified as companion animals (dogs, cats) enjoy much more progressive protections than that of cows or pigs, even though everyone agrees that all of these species are sentient. Based on this, it is clear that more is being considered with regard to animal protections than sentience alone, particularly the use or benefit of NHAs to humans rather than the characteristics of the NHA itself. In fact, I would surmise that these external considerations hold greater weight in determining our treatment of animals over sentience or any other scientific factor. For instance, companion animals get more protections because of their station in society as “man’s best friend.” Cows and pigs are viewed as merely products used to create food humans like to eat and as such, their sentience is viewed as more of a nuisance than anything else. As a result, consideration of their sentience is deemed less important than that of companion animals’ sentience. Nevertheless, I am certain that if cows and pigs were not found to be sentient, the idea of providing them any legal protections beyond that of traditional property would not even be up for discussion.

Despite being classified as sentient, fishes seem to fall even below cows and pigs with regard to being entitled to extra protections as a result of their newfound status. This may be due to the sheer number of fishes that are utilized by humans; it may seem like too overwhelming a task to afford them additional protections because they are sentient, both from a logistical and financial perspective.

In the EU, NHAs are given special consideration when laws are created around farming practices to ensure higher welfare for these feeling creatures and the EU does recognize fishes as sentient beings.[16] Yet, little is being done to protect the approximately 1.2 billion fishes who are farmed in the EU annually.[17] Fisheries are included in the language of Title II of The Treaty that addresses the aforementioned welfare requirement, but that is where the protection currently ends.[18]

Most recently, the UK government announced an amendment to its Animal Welfare (Sentience) Bill that recognizes lobsters, octopuses, crabs, and all other decapod crustaceans and cephalopod mollusks as sentient beings.[19] Unfortunately, like the current state in the EU, there are no immediate plans in the UK to amend any existing laws or policies around the fishing or aquaculture industry as a result of this determination.[20]

One would certainly hope and expect that the EU and the UK will eventually address fish welfare in the same way it addresses the welfare of chickens and cows. I do think that change is coming, at least in the EU. Several MEPs have made the case to the European Parliament for improving aquaculture standards in the EU, and a survey of public opinion indicates that 79% of EU citizens believe that fishes should receive the same protections as other farmed animals.[21] The EU has historically been at the forefront for better farmed animal protection, and I believe that is is only a matter of time until its laws about aquaculture catch up to its laws concerning animal agriculture. Eventually, fishes will be viewed in the same way we view other NHAs used in agriculture, which still leaves a lot to be desired, but at least affording the protections that a cow or pig receives to fishes would be a start in improving their welfare.

Who Is Left Behind?

All of this discussion begs the question, what other NHAs are sentient that are being overlooked? For instance, science uses the presence of a central nervous system as a factor in determining sentience, and some studies suggest that insects have a central nervous system.[22] Therefore, if the main requirement for additional protections is that a NHA has to be sentient, and the case can be made for the sentience of insects, wouldn’t that mean protections put in place for insects that could potentially be the same as those that apply to cows and pigs? It may seem preposterous to some to grant additional legal protections to insects, but the same could be said about the viewpoint on fishes just a a few years ago, and while fishes are not quite there yet with regard to better legal protections based on their sentience, they are getting closer.


By relying so heavily on sentience as a qualifier for additional legal protections beyond that of traditional property, we run the risk of excluding NHAs because of our limited understanding of where they fall on the sentience meter and our tunnel vision surrounding this classification as paramount. Therefore, I think it is best to assume that all NHAs deserve protections beyond those afforded by a classification of traditional property status, regardless of whether or not sentience has been determined or detected, and regardless of other factors, such as station in society or population of that species.

One thing is for sure in our current legal system: at this point, sentience may not be a guarantee for greater legal protections than that of traditional property, but NHAs cannot hope the have those additional protections without a sentience classification. However, it is important to remember that just because we cannot see the existence of sentience in a NHA in terms we currently understand, does not mean they do not deserve protections.


[1] Jan Hoole, Here’s What the Science Says about Animal Sentience, (November 24, 2017),

[2] Law No. 76-629 of July 10, 1976,

[3] The Lisbon treaty,

[4] Rajesh K. Reddy, Enshrining Animal Sentience into Law: Global Developments and Implications (January 22, 2020),

[5] Ross Kelly, Recognition of Animal Sentience on the Rise, (May 14, 2020),,in%20its%20laws%2C%20in%202013.

[6] Merriam Webster.,A%20sentient%20being%20is%20one%20who%20perceives%20and%20responds%20to,touch%2C%20taste%2C%20or%20smell.

[7] Faunalytics, The Importance of Sentience in Animal Legislation, (April 16, 2015),

[8] Jacy Reese, What is Sentience? Sentience Institute (June 21, 2018),

[9]Victoria Braithwaite, Do Fish Feel Pain? Oxford University Press, (2010).

[10] Animal Ethics, Criteria for Recognizing Sentience,

[11] Matthew Chalmers, Do Fish Feel Pain? The Science Behind Fish Sentience, Sentient Media (April 16, 2021),

[12] K.P. Chandro, et al, Can Fish Suffer? Perspectives on Sentience, Fear, and Stress, Applied Animal Behavior Science, Vol. 86, Issues 3-4, Pg. 225-250 (June 2004),

[13] Compassion in World Farming, Why Fish Welfare Matters: The Evidence for Fish Sentience (2019),

[14] Chalmers, supra note 2.

[15] Universities Federation for Animal Welfare, Farmed Fish Welfare,

[16] Compassion in World Farming, EU Parliament Set to Develop a Position on Fish Welfare (October 3, 2021),

[17] Id.

[18] The Lisbon treaty, supra note 2.

[19]Department for Environment, Food & Rural Affairs, et al., Lobsters, Octopus, and Crabs Recognised As Sentient Beings, (November 19, 2021),

[20] Id.

[21] Compassion in World Farming, supra note 3.

[22] Animal Ethics, What Beings are Conscious?,


Cynthia von Schlichten