Not every detention encounter with the police results in a citation. If it does result in a citation, they have preformed a non-custodial arrest. If they want to search you, they can perform a full-custody arrest even if it's for a misdemeanor that is only punishable by a fine(Atwater v. Lago Vista).

I very strongly agree with Janice Rogers Brown's opinon here: http://www.volokh.com/posts/1125942214.shtml

edit: Hmmm after reading a few things, I now think it depends on the jurisdiction whether they define receiving a citation as a non-custodial arrest.

> the police do not gain the right to search your vehicle.

Depends. Just need probable cause. Motor vehicle exception.

>But they do have that right if they arrest you.

Depends. Search incident to arrest exception with automobile caveats. After Gant, if the arrestee no longer has access, or no reason to believe that evidence of the arrest offense will be found, not ok. (But still maybe ok to impound and inventory.)

"Probable cause" is all an officer needs to arrest you, too.

Right, but the "probable cause" is technically different -- for a search without arrest, they need probable cause to believe that there is contraband in the car, for arrest they need probable cause to believe you have committed a crime. Given that possession of contraband is itself a crime (though generally one with a mental state requirement), there is quite a lot of overlap between the two kinds of "probable cause", but they aren't equivalent.

Yeah, that seems like an important distinction. Thanks.

I won't repeat dragonwriter, but I wasn't criticizing, just pointing out that your statements aren't absolute rules. They just tend to be the simplest statements of the rules that exist.

Also with arrest, lower standard for if they think evidence will be found. It's the RAS-like "reasonable to believe" that evidence of the crime will be discovered.