Secrecy around police surveillance equipment proves a case’s

The case against Tadrae McKenzie looked like an easy win for prosecutors. He and two buddies robbed a small-time pot dealer of $130 worth of weed using a BB gun. Under Florida law, that was robbery with a deadly weapon, with a sentence of at least four years in prison.

But before trial, his defense team detected investigators’ use of a secret surveillance tool, one that raises significant privacy concerns. In an unprecedented move, a state judge ordered the police to show the device — a cell-tower simulator sometimes called a StingRay — to the attorneys.

Rather than show the equipment, the state offered McKenzie a plea bargain.

Today, 20-year-old McKenzie is serving six months’ probation after pleading guilty to a second-degree misdemeanor. He got, as one civil liberties advocate said, the deal of the century.

McKenzie’s case is emblematic of the growing, but hidden, use of a sophisticated surveillance technology borrowed from the national security world for use by local law enforcement. It shows how a gag order imposed by the FBI — on grounds that discussing the device’s operation will compromise its effectiveness — has left judges, the public and criminal defendants in the dark on how the tool works.