Over the past 20 years, canine units have developed a reputation for reliability. However, many police departments are reluctant to undertake the increased responsibilities and liabilities that a canine unit requires. The police department of Lakewood, Colo., has used canine units and has found them to be particularly useful in night watch patrol work. Because deploying a police dog to stop assaults, to overcome resistance by those arrested, or to defend another person can be interpreted as use of force, those uses must be in compliance with a police department's written policy on the use of force. In addition, it is important to have written standards that specifically articulate policies for and limitations on the use of canine units. Police personnel selected to become handlers must be carefully selected and trained. A head trainer must be selected to train staff and dogs and to manage the program. The dogs in the program must be trained, cared for, and compatible with their handlers. The average cost of maintaining each dog is about $1,200 per year.