Shoot it...there is no local, state, or federal law that I know of that says a civilian cannot own or shoot ammunition marked law enforcement only. Other states may be different, but in Texas the above is true.
There are many, many websites (sgammo, luckygunner, and many others) that sell law enforcement only marked ammunition to the general public.
The only caveat is with +P or +P+ ammunition it should only be shot in modern firearms in good condition, and it probably says that on the ammunition boxes also.
Just my .02,