Because of their size and their overall intelligence, boxers can be ideal dogs to be trained to assist law enforcement officers with police work. Boxer dogs are large enough and strong enough that they can take down or restrain a perpetrator if needed, and are smart enough that they can be taught a variety of different skills which can help the police with their work. The boxer breed carries with it a long tradition of police work, as even the early boxers of the beginning of the 20th century were being used as police dogs in Germany while the breed was still becoming popular in the rest of the world.
One of the more popular uses of boxers as police dogs is training them to be what's known as a public order enforcement dog. Boxers are a popular alternative to German shepherds in this role, and are used to chase down and hold suspects in order to assist the police with making an arrest. The dogs may also be used to help maintain order or diffuse a tense situation, as the threat of having the dog released toward them can make many suspects or perpetrators have second thoughts about resisting arrest. Commands taught to the boxers are often taught in languages other than the language that people in the area speak, so as to keep the dogs from accidentally hearing a command in casual conversation as well as to prevent suspects from being able to call off the dogs by giving the appropriate command while being attacked.
Even the coloring of boxers plays a part in their popularity as police dogs, since many dogs with a striped or brindle coat (as well as coats of darker solid shades of brown) can be much harder to see at night and maintain an element of surprise when taking down a suspect. It is believed that this quality led to the falling out of favor of white boxers and the subsequent failure to recognize white boxers as a legitimate coat color by major kennel clubs; the white coats of the dogs were too easy to recognize in the dark, so their value as police dogs was greatly degraded.
Because of the important role that boxers and other police dogs can play in apprehending suspects and keeping the peace, many jurisdictions around the world take special precautions to help make sure that the dogs that they use remain safe. A number of police precincts have begun using specialized body armor for their boxers and other police dogs in order to protect them from being shot or otherwise assaulted, and try to keep their dogs socialized with people by having them live in the homes of their handlers. In many places the penalty for assaulting or otherwise harming a police dog is the same as if you had done so to a uniformed officer, thanks to laws that were enacted to deter violence against the dogs that the police force uses.