I learned on March 10, 1990 that for all practical purposes the Fourth Amendment does not exist. The cops can write an anonymous letter to themselves, tell a bunch of lies under oath, get a search warrant that isn't supported by probable cause, serve the search warrant with drug-sniffing dogs and a battering ram and submachine guns and body armor and video cameras, seize $1,400 in cash that they don't have probable cause to seize, get ordered by a federal judge to return the money immediately, sit on the money for another ten days, and finally give it back under threat of a jail sentence for contempt.
And I still couldn't sue them. It was all an "honest mistake," so they have immunity.