Whether it is to complain about or commend a police officers actions, sometimes finding out a badge number is necessary. This is public information but you will need a name in order to find out the badge number of a specific officer. Aside from asking the officer directly, you can find this out through the law enforcement agency that particular officer is a member of.
Contact the Local Law Enforcement Agency
By either going into the main police station or calling in you can request an officer's badge number by providing his name. This is public information, so the receptionist must disclose the number promptly. If you do not have the officer's name there is very little they can do for identification of the officer to provide the badge number. If there was an incident with the officer that you'd like to press charges on, a transcript of dispatches may be provided.
The law enforcement agency's employment records are another option. By going to the town's archives or by searching at the police headquarters' archives you can find all officers employed and their badge numbers. Again, this will require a name in order to correlate with a number.
Use Online Resources
You can use online resources, such as PoliceOne.com, to find a comprehensive list of law enforcement agencies across the country and ask them directly to perform a police badge number lookup. Bear in mind that state laws may vary regarding police badge numbers. For example, the California Penal Code requires all officers to wear a badge with an identifying number, but other jurisdictions may not have this requirement.