Drug test for tenants?

I own 4 rentals, Last December a drug dealer payed a vistit to one of my tenants resulting in a gun fight. I had to close and repair all 4 apartments at a cost over $19,930.00 USD. I have decided to require a drug test as part of the back ground check before any one can live in one of my units. I all ready have retrained a lawyer. But i was wondering what the PR impact of this is going to this. Thus i would like your 2 cents, if you have more than 2 cents to give, feel free.