Can policemen swear at you?

Having been a "street cop" for 22 of the 30 years I spent in law enforcment, I can tell you emphatically that officers do use profanity (they are human after all) and often times use profanity intentionally for its effect. As far as legality, I serious doubt there is any law in the UK that prohibits any citizen, including the police, from actually using the type of profanity you described; however, all police departments have what is called a "code of conduct" which likely prohibits an officer acting in a way that is "unbecoming" or "unprofessional" (whatever that may mean). I know from personal experience that using profanity or swearing isn't always considered unbecoming or unprofessional. It all depends on the cirstances. Many times I used profanity to get somebody's attention and let them know I wasn't f---ing around. Get the picture? Of course this was always done at the risk of receiving a citizen's complaint. But I never knew or heard of an officer getting more than an informal reprimand for language. Most often, the officer explained the situation and cirstances and the supervisor agreed that the profanity was acceptable. Given the situation you described above, as a supervisor I would not hold that officer accountable or at fault for using the term you described. I can guarantee you that if there is one situation where officers are given great latitude, by both supervisors and the courts, it is when they have a person in custody or are in the process of arrest, and a third party gives the appearance of interfering in any manner, even if it is simply verbal in nature. It appeared the officer you described was rather successful with the use of one word, which is why it happens. Hope this helped.