1) Before obtaining a search warrant, investigators had to try to obtain the evidence in another way, such as by subpoena.
2) The authorization for the warrant had to come from either the U.S. attorney or an assistant attorney general. (Rosenstein is deputy attorney general, a higher position than assistant attorney general.)
3) The prosecutor had to confer with the criminal division of the department before seeking the warrant.
4) The team conducting the search had to “employ adequate precautions” to ensure that they weren’t improperly viewing privileged communications between Cohen and his clients.
5) The search team would have included a “privilege team,” including lawyers and agents not working the case, which would work to ensure that investigators conducting the search didn’t see privileged communications.
6) The investigators had to develop a review process for the seized material.