https://www.aclu.org/know-your-right...ped-by-police/
Back in the heyday of the 60's there was an underground newspaper at UT called "The Rag" and they would regularly post articles advising folks what to do when stopped by a cop. Essentially, you were at ask,"Am I under arrest?" and if the cop said no, you were advised to walk away.
Never had the chance to test it, thankfully.