possible

but not necessary evidence, as evidence would imply a crime. But when it comes to police harassing activists, or outright mislabeling them as terrorists, there are many fully legal things you still might prefer the police not to have. Lets not forget that boarder police has in the past tried absurd things like trying to seize Attorney-client privilege protected information from a US attorney.

Through most likely many people setting up and using a duress pins never truly think this thought from a legal POV.