This has to be the top comment in this thread. If you think about it why does anyone have to follow the law? Because there are consequences for when they don't.

This has to be the top comment in this thread. If you think about it why does anyone have to follow the law? Because there are consequences for when they don't. In this case, as my parent OP correctly states, there's legal precedent and case law on what a reasonable suspicion is. The agent should be able to go to a court, in front of a judge and be able to state what made him/her suspicious of you. If they can't, all evidence they collected during that search will be thrown out. That could basically kill the case. That'd be the motivation for the agent to at least come up with a plausible story on why they want to search you.