The decoys prevent sharers downloading songs and enable record companies to track down the users.
Another tactic being employed is to plant decoys on file-sharing sites.
We manufacture tree stands, bowhunting packs and accessories, and waterfowl decoys, giving us a field side seat at the forefront of these migrations in hunting.
In real life, there might be lots of decoys, and they would be identical in shape to the real target.But politically, of course, it was a pleasure to hit the target, particularly at a time when doubts about the whole idea of sharply increased spending on missile defences are growing among Democrats.
And decoys can be fired to trick the missile's homing sensors and lure it away from the vessel under attack.
The lack of atmosphere in space means that missiles travel predictably, but it also means that decoys such as balloons move identically.
Stopping a missile in its boost phase is an attractive idea because the missile is unable easily to deploy decoys or to fragment into many sub-munitions.
A report issued in April by the Union of Concerned Scientists argued that any country clever enough to design ballistic missiles would also be able to make decoys of sufficient sophistication to fool the interceptors.
Even if decoys can be identified, each radar blip may require several seconds or more of analysis.
There is no point in having a missile-defence system that cannot prevent such an attack, says Mr Woolsey.It might, however, be possible to shoot down missiles or rockets before they reach space and eject decoys or place a nuke-carrying satellite in orbit.
And if it cannot spot the real target, it is developing interceptors with multiple "kill vehicles" to destroy decoys too.
