There are legal precedents for the defence of reasonable force in criminal law. A Christian group in the UK called Operation Ploughshares broke into an air field, did millions of pounds worth of damage to an airforce plane, then handed themselves in to the police. In court they pleased not guilty to wilful damage on the basis they were preventing a crime. The crime they were preventing was genocide, which is a criminal offence under international law. They argued that the plane was going to be sent to Indonesia, and the Indonesian military would be using it to commit genocide in East Timor.

The jury agreed with their legal defence, and those who damaged the plane were aquitted.

There are plenty of other examples as well as the above case and the drunken cop one. The most obvious would be using minimum force to prevent someone else being raped, assulted, murdered. What do you think we should do in this situation. Wag our finger at them? Wait for the police to arrive, by which time someone is dead? Similarly with the raids on battery farms. The SPCA do their best, but they have limited resources and cannot prosecute every establishment that breaches the Animal Welfare Act.