Ah, in my Civil Liberties and Rights class we had this case during our Moot Supreme Court exercise last week. My court, after some heated and illuminating discussion, ended up voting to unanimously overturn the law.
Probable cause? What's that?
There would, obviously, be probable cause when the person is arrested. Frankly, it would be a safety issue as well. The person might have something that he/she could use to cause personal injury.
These strip searches actually occur before a magistrate even determines whether their arrest had probable cause. And in this specific case, there certainly wasn't probable cause of anything: Mr. Florence was arrested only because a computer error had failed to purge an invalid arrest warrant from years before.
As for the safety argument, it's honestly bollocks; even before the strip search, the detainees have to go through metal detectors and face extensive pat downs. There's no reason a prison detainee should be forced, absent probable cause, to be stripped naked when such security measures are already in effect.
The arrest determines that there is probable case. Now, if Mr. Florence wants to sue on the basis that the original arrest did not have probable cause (and I'd agree that it didn't) that is fine. The strip search is only a consequence of that arrest.
I think the idea that there should be judicial review prior to an arrest and processing is lunacy.
A person could have non metallic weapons, conceivably, i.e. a garrote of some type. There is also the possibility of contraband.
