It's a judge's call to define probable cause, not a librarian's - that's why law enforcement officials are required to secure a warrant before conducting searches.
actually, if I agree that law enforcement can search my home, then they can search my home. I don't need a judge to tell me whether or not it is reasonable. I have that option, of course. But a library is a public institution. No one should expect that anything they do in a library would remain private. I never have. Whether the feds have a right to go into a local library and order folks around is another matter. Local cops should have been able to do it. But that's just my opinion.
"It's a judge's call to define probable cause, not a librarian's - that's why law enforcement officials are required to secure a warrant before conducting searches."
Couldn't this fall under the category of a hot pursuit? It reads like a terror threat was recieved, immediately traced to a specific location, and when the cops arrived, a bureaucrat says not so fast.
If someone is shot on the street in front of the library, and the perp is seen to run inside, do the police need a warrant to pursue?