&gt; The only thing keeping laser microphones...<p>The legality has nothing to do with it, as it has been demonstrated over and over that law enforcement will employ methods that can charitably be described as &quot;legally questionable&quot; and then attempt to hide it (see stingray).  What is stopping them is limitations imposed by the physical world - both in number of windows and the fact that laser mics don&#x27;t work the way they&#x27;re portrayed on television.  This is the reason why digital key escrow is infinitely more dangerous than physical key escrow (like fire department lockboxes).