For example, in the United States, most spring-guns are loaded with non-lethal caliber or shot to avoid liability arising from the use of deadly force in protection of a property interest. Posting clear and unmistakable warning signs as well as making entry to spring-gun guarded premises difficult for innocent persons, such as high walls, fences and natural obstacles, are significant ways to reduce potential tort liability arising from the spring-gun's wounding of a careless or criminal intruder. Important US lawsuits regarding trespassers wounded by spring-guns include "Katko v. Briney". "Bird v. Holbrook" is an 1825 English case also of great relevance, where a spring-gun set to protect a tulip garden injured a trespasser who was recovering a stray bird. The man who set the spring-gun was liable for the damage caused.