This strategy requires that the man defending the ball-handler is very quick, aggressive, and willing to get in close, but also agile enough to do so without committing a foul. Once it is determined that the offense is about to attempt a pick-and-roll, the man defending the ball-handler should "belly-up," i.e., get as close to the ball-handler as possible, so that he can squeeze by the pick. In practice, this usually means that the defender must outrace the ball handler to the pick so that the ball handler actually ends up being the one going around the pick and winds up out of position. As a result, the man defending the pick-setter can continue to guard his man unabated. This technique is considered the most effective way of countering the pick and roll; however, as mentioned, it requires a special defensive player.
The defender of the ball-handler must also be careful to not over-commit toward the pick too soon; if he does, the pick-setter can readjust to screen the defender off as the ball-handler heads in the opposite direction of the pick.
Rather than outracing the ball-handler, this technique is designed to "trap" him too far away from the action to be able to complete the play effectively. As the pick-setter gets into position, his defender must go to the top of the pick and close off the alley that the ball-handler intended to go through. As a result, the ball-handler's defender can now close in on the ball-handler from behind, using the pick-setter himself as an additional de-facto defender. There are some serious downsides to trapping, however:
First, the defender initiating the trap can only get into position once the ball-handler has committed himself to using the pick, but must do so in time to get into position for the trap (if he's still moving, a foul will be called).
Second, if the defender moves too quickly, he will effectively be abandoning the pick-setter, who can roll out early for an easy pass. In essence, the play will achieve its goal without the pick and roll having even been run.
Third, since both defenders will be guarding the ball-handler, one offensive player will be open. Even a great trap will only work for a short time. Therefore, this technique is best employed when the pick is set at the top of the key (to prevent an easy short pass down low) or near a sideline (so the sideline can be used as an additional defender).
Since trapping will always leave someone open, the remaining three defenders should sag off of their men and play more of a zone-defense, guarding the passing lanes. Therefore, trapping requires excellent team communication.
This technique is designed to allow the pick and roll, but forces the ball-handler to wind up out of position. After the pick is set, the pick-setter's defender must go to the far-side top of the pick, effectively setting a double-pick, but further away from the basket than the first. The ball-handler's defender, meanwhile, must quickly go underneath the pick (which prevents an easy roll-out by the pick-setter) since the ball-handler will not have an open shot so quickly. This is the first switch. As the ball-handler is now forced the go around the pick-setter's defender, the ball-handler's defender meets him at the end of the double screen. The pick-setter's defender quickly returns to his man before he can roll out; the second switch. Since the ball-handler is now further out than the play intended, it will be more difficult for him to hit the pick-setter with an easy pass.
The risk of this technique is that if the offense recognizes it quickly enough, the ball-handler can pull away from the pick, leaving the defense with a tough choice: either the pick-setter's defender must drag along with the ball-handler, leaving the ball-handler's defender to guard the pick-setter (resulting, usually, in a serious height mismatch), or the ball handler will be left open for an open jump shot.