I was at a competition pistol class once in preparation for the FNH 3-Gun Championship (videos here) when something disturbing happened: the person next to me had a negligent discharge straight into the ground about three feet in front of him while drawing from the holster. He was lucky -- Tex Grebner (IGOTD member and not helping the 2A crew) was less so. What caused this negligent discharge? A SERPA Holster.
Holsters with "active retention" use a mechanical device of some sort to restrain the gun and keep it from flopping out of the holster.
The device can be as simple as a leather strap or as complex as a digital electromechanical device. No matter what it is, the point is that it needs to be removed (or "defeated") before the gun can be drawn. This is especially appealing for people who need to carry a firearm and might do a lot of moving about, such as me and my fellow 3-gunners. I know at least four people were disqualified this weekend for pistols falling out of their holster and not using active retention. In our style of competition active retention isn't politely suggested -- it's almost required equipment.
I figured out pretty quickly that the key to a good 3-gun holster is retention, and to me the SERPA holster made the most sense at the time. It used a retention device that locked the trigger guard in place when the gun was holstered and was easily defeated by pressing a button conveniently located where your finger would normally index along the side of the frame. It was a natural place for your finger to be, but not a natural movement. Putting pressure on the button and then quickly drawing the gun meant there was a possibility that your finger would slip into the trigger guard and accidentally pull the trigger, especially when the gun was a striker fired Glock like my classmate was using.
After the ND I immediately went to my trunk and swapped the SERPA holster I had been using...
for a Safariland ALS holster I purchased for the UOFA class I took a few months back (they didn't allow SERPA holsters). ALS holsters have an active retention mechanism that slots into the ejection port of the pistol and uses a lever by your thumb to release the gun, requiring no trigger finger work. I had always assumed that SERPA NDs were caused by idiots not using the thing properly and that I would always be safe running full tilt down a course of fire, but the person next to me was no idiot. He was a former Secret Service agent and retired Special Forces soldier, a man with more experience than I could imagine. And he almost shot his foot using a SERPA.
After I swapped holsters not only did I feel more secure about my ability to keep my blood on the inside but the new holster also shaved about a second off my draw time. And after competing in the FNH 3-Gun Championship this weekend using the ALS holster instead of the SERPA I have no idea why anyone would use anything else. It's faster, more secure, and doesn't come with the increased possibility of a ND.
Guns, when handled improperly, are dangerous.
But even more dangerous is safety gear that doesn't live up to expectations or even encourages accidents. Like the SERPA holster. And like lawn darts before it, so should the SERPA holster go gentle into that good night.