What is the ruling on working in the training of police dogs for guarding establishments and personalities, and is it permissible to keep a guard dog designated for work in the private home's garden?

The Sharia prohibits keeping dogs except out of necessity, such as for hunting, guarding livestock, or crops. It punishes those who violate this by decreasing their reward. By analogy, it is permissible to keep dogs for detecting crimes and pursuing criminals, as this entails a benefit that is recognized by the Sharia. Ibn Abd al-Barr mentioned the permissibility of acquiring dogs for benefits and warding off harms, and that scholars did not object to this. The Permanent Committee permitted the use of police dogs for detecting drugs and explosives, with the obligation to be cautious of their impurity and to wash whatever touches clothing or the body from them. It is permissible to keep a dog in a garden separate from the house if its acquisition is for a permissible need, but it is preferable to keep it at the place of work if possible.