Yes, physical resistance to authority is, more often than not, a bad idea, and hopefully most of us know why (even if you're right and even if you're being attacked, they're not above planting a gun/drugs/other thing on you to justify beating/killing you). But the Supreme Court has said, most emphatically, that there is no "requirement to identify oneself", regardless of whether an officer has probable cause to stop and question the individual. Brown v. Texas, 443 US 47 (1979). I'd repost the relevant excerpts from this great case again if I hadn't already posted it so many times to so many different fora. Suffice it to say, regardless of whatever else may be at issue, the "ruling establishment" (i.e., the highest legal authority in the country) has stated that there is no requirement to identify oneself. Just had to get that off my chest. We now return you to our regularly scheduled stuff.