Now, I could be wrong (I often am) but I think if they go to arrest someone and the evidence is in plain sight, a search warrant is not needed. They may need a search warrant to look for further evidence, but I'm not sure.

Um, here's a legal definition of a search warrant.. if you can understand all of the legalese. ;-)

http://www.lectlaw.com/def2/s117.htm

"You need me. You wouldn't be much of a hero without a villain. And you do love being the hero, don't you. The cheering children, the swooning women, you love it so much, it's made you my most reliable accomplice." -- Lex Luthor to Superman, Question Authority, Justice League Unlimited