Under Virginia law it is generally illegal for an officer, without a warrant, to arrest someone for a misdemeanor not observed by the officer (there are exceptions including shoplifting, assault and battery, brandishing a firearm - when a witness ID's the offender). Of course, the US Supreme Court has left us in a wonderful position by solidifying a wonderful dichotomy in Virginia: the unconstitutional and the illegal. Under Moore, it is quite possible for an officer to arrest someone illegally, but not uncostitutionally. An example would be if someone told an officer that John Smith stole his (worth less than $200) bike. Theoretically, the officer cannot arrest Mr. Smith. In reality, because the arrest would not be unconstitutional, there is no check on the officer arresting Mr. Smith without proving probable cause to a magistrate and getting a warrant (outside of the extremely theoretical potential civil liability).
I started mulling this over in relation to reasonable articulable suspicion of criminal activity. Does this dichotomy affect the standard or was the standard already so low as to not be effected by it? A typical reason to ponder this would be that Victim calls dispatch and reports that his ex-girlfriend is outside his house keying his car (all the while screaming at her that he's calling the police on her). ExG, not being a 100% idiot, gets in her car and drives away before police get to the house. On his way to the house, Officer spots ExG's car leaving the subdivision. Can Officer pull a 180 and stop ExG?
1) Yes, he always could because he has reasonable articulable suspicion of a crime, or
2) No, he cannot because he cannot legally arrest her without a warrant and has no suspicion of an ongoing crime, or
3) Yes, he can because the US Supreme Court has empowered the officer to constitutionally arrest her illegally. He can pull her over to arrest her and not bother with reasonable articulable suspicion.
I think that prior to Moore 2 probably was the better argument. However, now that Moore is the law of the land I wonder if 3 might not carry the day.