The term "law enforcement officer" is defined in different jurisdictions in different ways and is defined in different ways for different purposes. For example, a criminal code might define law enforcement officer in reference to arrest power, while another statute might used the term for H.R. and licensing regulations, and a third might use a functional definition for eligibility for a certain kind of tax deduction under state law. Not every jurisdiction has every kind of law enforcement officer either.
The term "law enforcement officer" would almost never include a judge or prosecuting attorneys, but would sometimes include a law clerk for a judge. This is because law clerks, especially in rural areas, often have a dual appointment as a law clerk (basically a lawyer acting as a research assistant for a judge) and as a bailiff who is an officer of the court charged with maintaining order and security in the courthouse, or at least in an individual judge's courtroom. A bailiff would often be classified as a "law enforcement officer."
Law enforcement officers would ordinarily include
- Municipal police.
- Town Constables.
- County sheriffs and deputy sheriffs.
- Marshals including U.S. Marshals.
- Some Park Rangers.
- State police.
- Mounties (i.e. Royal Mounted Police in Canada).
- Texas Rangers.
- College or university security officers.
- Transit system security officers.
- FBI agents.
- Secret Service agents.
- DEA agents (i.e. drug enforcement agency).
- ICE Agents (i.e. immigration and customs enforcement)
- General services administration officers (i.e. federal building security).
There would be differences from jurisdiction to jurisdiction and based upon the context in which the term was used over whether some of the following persons would be law enforcement officers for particular purposes:
- Coroners and deputy coroners.
- Military police.
- Parking enforcement officers.
- Ordinance and building code enforcement officers.
- Crossing guards.
- Law enforcement forensic lab employees and CSI officers.
- Diplomatic protection corps employees of the State Department
- Justices of the peace (who historically had both judicial and law enforcement duties although now this is mostly the title of a non-law enforcement judge).
- Confidential informants under contract.
A Florida statute cited as an answer to a previous question you asked about impersonating a law enforcement officer included the following list, from which I have marked in bold those that would often not be considered law enforcement officers:
- officer of the Florida Highway Patrol
- officer of the Fish and Wildlife Conservation Commission
- fire or arson investigator of the Department of Financial Services
- officer of the Department of Financial Services
- officer of the Department of Corrections
- correctional probation officer
- deputy sheriff
- state attorney or assistant state attorney
- statewide prosecutor or assistant statewide prosecutor
- state attorney investigator
- police officer
- lottery special agent or lottery investigator
- beverage enforcement agent
- any member of the Florida Commission on Offender Review and any administrative aide or supervisor employed by the commission
- any personnel or representative of the Department of Law Enforcement
- a federal law enforcement officer as defined in s. 901.1505
Some of bolded categories are marked that way because some people identified would count as law enforcement officers, but clerical and administrative personnel in those offices would ordinarily not be considered law enforcement officers.
Correctional officers are frequently considered law enforcement officers for some purposes and not others.