The tort of trespass is similar to that of nuisance, though there are differences. For one; trespass is always a deliberate action, and for another; it concerns more directly a physical presence on another's property. Trespass normally involves one or more individuals actually going onto another's property without the consent of the owner, but in recent years, there have been some tort cases where trespass has been successfully used to combat pollution.

Though trespass can be used to win civil cases involving pollution, it's by no means always successful. The situation has to fit the criteria for trespass exactly or the case will fail. The depositing of the pollutant in question has to be direct; this means that pollutants wafting in on the breeze from a distance or carried to your land by tidal water don't qualify.

Let's say you own a wild animal (an animal not ordinarily kept as a pet and one that has a potential to harm people) and that animal escapes. According to the common-law principle of strict liability, a court will likely find you liable for any harm the animal does even if you were in no way negligent. This reflects the belief that if you do something so inherently dangerous, you should be liable for any harm that results whether or not you actually acted carelessly.

Today, this principle has been expanded to include such things as harm caused by chemicals escaping from factories or sewage leaking from drainpipes.