When is willful interference to other amateur radio stations permitted?

The FCC rules strictly prohibit willful (intentional) and malicious interference in the Amateur Radio Service under all circumstances. There are absolutely no exceptions to this rule. Even if another operator is deliberately breaking the rules, acting obnoxiously, or causing a nuisance, you are never allowed to intentionally jam or interfere with their transmissions. Amateur radio operators do not have the authority to enforce rules via interference. Always remember that two wrongs do not make a right in amateur radio; self-policing means reporting severe issues, not taking matters into your own hands on the airwaves.