Malkoff M91T MD3, 600 lumens constant, no drop down, small enough to always be on his Duty Belt, but long enough to tuck under his arm when checking Doc's, runs on 2 x 18500 (1700mah) rechargeable batteries for 1hr 23 mins (will also run on 3 x CR123's if his department supplies them).
The optional High/Low ring is a must have, it has a low of 25 lumens, which is suitable for checking documents etc. Simply untighten the head a fraction of a turn to activate Low mode, tighten head and it's back to High mode. Tail cap clicky switch can be pressed with whole of thumb pad for momentary flash when carrying out a tactical search etc.
The M91T is fitted with a TIR lens that provides more throw than a standard reflector but it still offers sufficient spill. It's not too bright, on high, for dwelling searches etc. but it's bright enough for open area searches.
Malkoff's fit in with the '
Keep
It
Simple
Stupid' philosophy which means he won't have any issues operating it in a high stress situation, which could be a life saver.
Malkoff's are built like tanks, they are very robust and reliable, they are simple to use and come with a lifetime warranty, they also offer an LEO discount.
I am not affiliated to Malkoff's, I'm a retired LEO and a very satisfied Malkoff customer, I carried Surefire lights for 20 years of my career but I would carry a Malkoff now.
With the High/Low ring installed the price is about $153 with the LEO discount.
I wish your brother-in-law a long and safe career!
The M91T is the middle one in the below photo (Top is a Malkoff Hound Dog V3 and bottom is a Malkoff MD2).