Originally Posted by PTravel

Anyone can make a citizen's arrest. You just better be right because, if you're not, you'll be liable for a number of things. My understanding is that citizen's arrest, like an arrest by a LEO, requires, at minimum, probable cause in the legal sense and also requires that the person making the arrest have witnessed the alleged crime. Someone making a citizen's arrest is held to all of the same legal standards as a LEO. I would not recommend that anyone try to effect a citizen's arrest except in the most dire of circumstances. If a TSO tried that on me, I'd sue the living crap out of him, as well as press criminal charges.

We were discussing bags of white powder. I do not know what the standard for a drug arrest by a LEO would be, but I'd bet it would be more than, "I saw an otherwise solid-looking citizen with a small bag of what appeared to be white powder pass through airport security." A LEO is within his rights to question someone about it. A TSO has absolutely no right to question anyone about anything. If a LEO is dissatisfied with either the responses to his question, the person's demeanor, or any of a number of other factors that a good LEO might observe, he might have grounds to detain. A TSO has no ability whatsoever to detain, and if he should try to do so, he has committed a battery, among other things.