It's actually worse than that. Assuming you do have something illegal in those boxes, they've pulled a legal maneuver whereby you are forced to claim ownership

It's actually worse than that. Assuming you do have something illegal in those boxes, they've pulled a legal maneuver whereby you are forced to claim ownership. It's an end-run around the 5th Amendment right against self-incrimination. They seized your property and require you to incriminate yourself to get it back. Lockboxes where the contents are legal will presumably be claimed by their owners, unless the contents are somehow embarrassing. Illegal lockboxes won't be claimed, and the FBI has effectively seized them without needing a warrant for the contents. I'll be surprised if the FBI wins this in court, but it won't make any difference. This will take years to hash out, and by the time it's done, all the legal lockboxes will have already been claimed. The illegal ones are presumably anonymous, and the FBI will just say "oh well, if they won't claim it then we don't know whose it is, so I guess it's ours".