A police officer is a sworn officer charged with enforcing the law.

Kinds of police departments

  • There are thousands of law enforcement agencies in the United States. The bulk of policing happens through local (usually city) police departments.
  • In addition to city police departments, there are also county level departments (usually called sheriffs), as well as numerous state and federal agencies.
  • Police departments very often have overlapping jurisdictions. Depending on where a perp is and what offense she commits, she might be arrested by officers from several agencies. For example, if I drive dangerously within a mile of the university campus in my hometown, I could be arrested by university police (a state agency), the highway patrol (a state agency), or my city police (a local agency), among others.
  • At the state and federal levels especially, there are numerous law enforcement agencies with specialized jurisdiction. Examples of this include the DEA (Drug Enforcement Administration), California State Park Rangers, coroner’s officers, Stockton School District Police, and the Los Angeles Police Department.
  • Whatever the agency, police are often called peace officers.
  • Private security has been a growing segment in the US. Some private security officers are armed. Some private security agencies are very well equipped. Training and standards vary hugely.

Police department organization

  • Although almost all police departments are organized along quasi-military lines, the specifics vary from one department to another.
  • Within a particular agency, especially in large departments, there are often bureaus or subunits with specialized duties (e.g., homicide, vice, traffic).
  • Local policies and procedures also vary widely.

Police officers

  • Entry requirements for police officers vary by agency. Most agencies require a thorough background check, including a psychological evaluation. Prior felony convictions almost always disqualify a person.
  • All agencies require training for recruits. The extent and nature of this varies. Some states, like California, have state-mandated training requirements for all agencies. Some do not. Some agencies run their own police academies. Some do not.
  • Today, about 11% of officers nationwide are women. About 12% are Black and about 9% are Latino.
  • There’s an increasing emphasis on better-educated police. Some agencies now require a college degree. Research shows that officers with more education use force less often and generate fewer citizen complaints.


  • Police have more discretion than any other component of the CJ system.
  •  The bulk of police work—and the bulk of arrests—are done by uniformed patrol officers (not by detectives).
  • Police have three primary roles: 1. maintaining order (keeping the peace); 2. providing service; and 3. enforcing the law. Most police calls fall in the first two categories.
  • Almost all agencies say that good communication skills—oral and written—are the most important qualities of a good cop.
  • While technology and forensics are increasingly important in policing as means of addressing problems, they remain secondary to good communication.
  • Despite what is shown on TV and in movies, undercover police work is rare.
  • Police may receive little training in dealing with diverse populations such as the mentally ill, the elderly, immigrants, LGBT people, and the homeless.

The US Constitution and police

  • The US Constitution places numerous restrictions on police powers. These restrictions apply to all public peace officers in all government agencies at any level. However, they generally to not apply to private agencies (e.g., private security) or private individuals (e.g., bounty hunters).
  • These rules are complex. If you’re writing about them, it’s best to do some research and get them right.
  • Although there are numerous exceptions, the general rule—the Exclusionary Rule—is that if police violate someone’s constitutional rights, any evidence the police obtain as a result of those forbidden acts will be inadmissible in court. In addition, victims of police misconduct can sue.
  • Under the 4th Amendment, searches and seizures must be reasonable. This often means that searches require warrants—but there are many exceptions. Arrests generally do not require warrants, although it may be useful for police to obtain them.
  • Under the 5th Amendment, confessions must be voluntary. However—and this is important—police must read a suspect his Miranda warnings only if 1. the suspect is in custody and 2. police are going to interrogate the suspect. Even when a suspect is in custody, he need not be Mirandized if there’s no intention to interrogate him.
  • Under the 6th Amendment, once charges have been filed against a suspect, she is entitled to have an attorney present during questioning and during some procedures.
  • There are a variety of rules about when police can use force and how much they can use. In general, deadly force is allowed only when an officer reasonably believes it’s necessary to protect victims, police, or the community.