<p>Internationally, there are inconsistencies between national, state and territory Codes, Acts and Regulations on the definition of animal and animal use for scientific purposes, particularly for non-invasive animal studies. Non-invasive animal studies of free-living animals use opportunistic methods such as observation of animals, their physical signs and/or collection of discarded tissues. This contrasts with invasive studies which typically involve some form of deliberate disturbance, capture, sampling and/or application of identification. Investigator expectations concerning animal use are influenced by perceptions about the level of impact on the welfare of any animals involved. Confusion and frustration can result when it is difficult to clearly differentiate between invasive and non-invasive methods, and which non-invasive methods can be denoted as scientific use of animals. Nevertheless, scientific uses are more strictly regulated than equally or more impactful activities such as hunting, fishing, wildlife management practices and citizen science. If the species and procedures included in an animal study meet the definition of animal use for scientific purposes, the study must be approved, monitored and reviewed by an ethics committee. This paper discusses definitions of animal and animal use, welfare impacts of non-invasive animal studies, ways to improve ethics processes and the benefits of obtaining animal ethics review.</p>