White-light tactics; Clint Smith, Massad Ayoob....
Flashlight or the more modern phrase;
white-light tactics have evolved greatly in the last 15/20 years.
9-11-2001 had a big part of that change IMO, as FAMs(Air Marshals) & counter-terrorist units became more active.
Reportedly, 80-85% of lethal force events take place in low-light(night). Having a white-light or using flashlight/sidearm tactics is smart.
Top instructors like Massad Ayoob, Clint Smith, Larry Vickers, Jeff Gonzales, John Shaw, Duane Dieter, etc all teach white-light methods & tactics for CQB(close quarter battle).
There are books, DVDs & online videos that can teach you how to properly use a light with your CCW pistol or weapon.
A active FAM designed a special tool to add to Surefire;
www.surefire.com flashlights. This ring device helps the shooter angle the bright light while deploying the pistol.
Some gunners & armed professionals dislike the 1913 rail type white lights but I think they have value under limited conditions. As noted, modern systems are now brighter & brighter. I've seen Fenix & Streamlight units that are powerful
and compact. I've watched Youtube.com reviews/T&Es where the bright light(s) sweep entire yards or light up dark rooms with ease.
I purchased a new Fenix PD 32 series in 2013. It was powerful but really burned thru Li batteries
fast.
A good tip; use high end Li 123A batteries like Surefire or Streamlight brands(available at Bass Pro Shop or some well run gun shops). I lost my Fenix on a business trip but may get a new PD 35 series white-light. It has a strobe feature & 850lum,
.