Wiring a federal agent or informant would have been legal.

But the feds crossed the line by secretly installing microphones in at least three locations outside a California courthouse in 2009 and 2010 and eavesdropping on private conversations, says a motion. It was filed by defendants in a criminal case over claimed manipulation of foreclosure sales by real estate investors to drive down prices, reports the Recorder(sub. req.). The filing seeks to prevent the use of hundreds of hours of recorded evidence against the defendants.

With the OK of the Department of Justice and FBI lawyers, the government made the warrantless recordings with electronic bugs hidden in a planter, a wall-mounted metal sprinkler box and vehicles parked near an entrance to the San Mateo County courthouse in Redwood City, the defendants allege. This violated the defendants’ Fourth Amendment rights, says a motion to suppress (PDF) filed Friday in the…