There are many cooks in the criminal justice system kitchen. Understandably, many folks confuse the different agencies and individuals involved. So, to help, here's a who's who in criminal justice. The following is not a conclusive list, but it at least explains who many of the major players are.
There are a bunch of law enforcement agencies out there, but unless you're involved in some pretty heavy stuff, odds are the local agencies would be the ones on the case investigating you. By local, I mean a city police department or a county sheriff's office. Your county sheriff’s department is a separate agency from your local city police department. Most folks simply lump them all together, but it doesn't hurt to be aware of the differences. Typically, only one agency will be involved in an arrest. But certainly more than one department can be involved in some capacity.
Police departments are your local city police officers. The Chief of Police is a city employee who’s appointed, not elected by the public. By contrast, your county Sheriff is an elected public official. He or she runs the Sheriff’s Department. All the officers who work for him or her are called Sheriff’s deputies. As a side note, many deputies prefer not to be called “officers.” The title implies local police, not county sheriff’s deputies. But don't worry if you call a sheriff's deputy "officer" or a police officer "deputy"; it's likely not going to be taken as a sign of disrespect. Also, in either police or sheriff's departments, when individuals rise within the ranks, for example, to a detective or sergeant, they are then called by their new title.
After local agencies, there are statewide agencies, such as the California Highway Patrol (“CHP”). All CHP officers are paid by the State of California, not locally. Their jurisdiction to enforce state laws is not limited to the local county or city. But, as a general matter and as their agency name clearly suggests, their investigations and arrests stem mainly from traffic stops on California's highways.
There are other agencies—both local and state—that make arrests. The county Probation Department, for instance, monitors those on probation, which often leads to arrests. Also, your local District Attorney’s Office most likely has its own investigators known as DA Investigators. They, too, have the authority to enforce state laws and make arrests. Generally, DA Investigators are former sheriff’s or police detectives with a lot of experience. They typically will work with prosecutors on unique or complex cases. They also help prosecutors in follow-up investigations, witness interviews, etc. with respect to the DAs’ caseloads in general. Additionally, other state agencies (e.g., Department of Insurance, Department of Fish and Game, etc.) have authority to enforce state laws.
Then there are the federal authorities. The Federal Bureau of Investigation (“FBI”), also as its name suggests, is a federal agency within the U.S. Department of Justice ("DOJ"). Their jurisdiction is not limited to California or local matters. They investigate and arrest violators of United States' laws, not state laws. Typically, they are not involved in the investigation of local cases, including murders (unless it was, for instance, a mafia-related murder or a terrorism investigation). The FBI is also thought of as an intelligence agency like the CIA and NSA. But, unlike other intelligence agencies, it's clearer to view the FBI's primary function as law enforcement or evidence-gathering for federal prosecutors in court.
The FBI is hardly the only law enforcement agency within DOJ. Among many others, there's the Bureau of Alcohol, Tobacco, Firearms and Explosives ("ATF") as well as the U.S. Marshals Service, which is actually the oldest law enforcement agency in the country. Additionally, outside of DOJ and within the Department of Defense ("DoD"), the Department of Homeland Security houses, for example, several federal agencies such as the U.S. Customs and Border Protection, Immigration and Customs Enforcement ("ICE"), Transportation Security Administration ("TSA"), Secret Service, Coast Guard, etc.—each with authority to investigate and arrest Americans (and non-Americans).
Again, I'm only touching on some of the law enforcement agencies out there. If your head's spinning by now, I can't blame you. But I'll try to simplify matters here. The bottom line is the the VAST majority of all criminal cases in state and municipal courts—the kinds of cases that you'd have to worry about if you picked up, let's say, a DUI—stem from arrests made by city police, county sheriff’s deputies, or CHP, not federal authorities. And, if the U.S. government is coming after you with every three-letter agency in the book, then understanding my blog post here is the least of your worries.
Similar to law enforcement agencies, there a lot of attorneys to keep track of in the criminal justice system. For here, I'll stick to the main hitters.
The District Attorney’s Office - The District Attorney or “DA” is a county elected public official responsible for prosecuting suspected law violators in court. The DA represents the People of the State of California. That’s why in court, the DA will refer to him or herself as “the People” or “the State.” Generally, the DA’s staff of hired attorneys are known as deputy district attorneys (“DDAs”). In other states as well as in San Francisco (and possibly one or two other California counties), they are called assistant district attorneys (or "ADAs"). But, it's all the same. Also, there are ranks within a DA’s Office one can rise to, such as the Chief Assistant or Chief Deputy DA. No matter where you are or what rank, however, most people simply refer to prosecutors as "DAs." IMPORTANTLY, many people don't understand that it’s the DA alone who decides whether to file criminal charges. Neither the law enforcement agency that made the arrest nor the alleged victims make the ultimate decision.
The City Attorney’s Office - Some larger cities have, in addition to a DA’s Office, a City Attorney’s Office that handles criminal prosecution. These offices prosecute lower-level non-felony offenses—namely, misdemeanors and municipal violations. The same prosecutorial discretion of DAs applies to deputy city attorneys.
The Attorney General’s Office - The head of the U.S. Department of Justice is known as the Attorney General. Additionally, each state has its own justice department and Attorney General. From a bigger picture point of view of U.S. government, there are three distinct branches—the executive branch (which includes the President of the United States); the legislative branch (i.e., Congress); and the judicial branch (the courts). The executive branch enforces the laws with the President at the helm. Within that branch is the Attorney General. The California Attorney General Office employs deputy attorney generals (“DAGs”) who, for example, represent the State of California in criminal appeals cases, but occasionally will also prosecute cases in state court. However, they generally only get involved when there’s a particular conflict of interest for the local DA’s Office in its prosecution of a particular individual (for example, when the DA’s son gets arrested).
The United States Attorney’s Office - The United States Attorney’s Office is part of the U.S. Department of Justice. Prosecutors for a U.S. Attorney’s Office are known as assistant U.S. attorneys (“AUSAs”). Their offices are across the country. In their criminal divisions, they are responsible for prosecuting U.S. crimes—often cases stemming from FBI investigations—in federal district courts, not state courts.
Criminal Defense Attorneys
The Public Defender’s Office - Public Defenders or “PDs” (not to be confused with the Police Department or prosecutors) are court-appointed attorneys assigned to represent those accused of crimes who cannot afford a private attorney. Per the Sixth Amendment of the U.S. Constitution, the government must provide attorneys to indigent defendants. As the name suggests, they are in public, not private, practice. Thus, they work for the public and are paid by the local county government, just like the local judges, law enforcement, and DA. They will generally fight hard for their clients, but are often overburdened with large caseloads. Typically, each office will have a Chief Public Defender who can either be elected or appointed. Similar to deputy DAs, the attorneys who work for the Chief Public Defender are Deputy Public Defenders.
Private Defense Attorneys - Lastly, I must of course mention my gig as a private criminal defense attorney. There is no special office or agency that private defense lawyers all belong to. We're simply in private practice and paid individually by our clients.
No matter whether an attorney is a DA, PD, or in private practice, all attorneys are "esquires" or "legal counsel", a term that can mean either one lawyer or a team of lawyers. Thus in court, you will frequently hear judges and lawyers refer generally to other lawyers as simply “counsel.”
The court system in the United States is a bit complex, but, to explain briefly, it’s divided into a state system and a federal system. Each system has three different levels—the trial court is the first level for either court system. A DUI case, for example, will not be charged in federal court. Rather, it will be charged in your local superior court or, perhaps, your local municipal court, which is a trial court of limited jurisdiction (e.g., traffic court, small claims, etc.). A federal crime will be prosecuted in a federal district court. The second level or intermediate level of courts in both the state and federal system are the appellate courts (known as "circuit courts" in the federal system), which is where folks go to appeal verdicts and decisions made in the trial court. Lastly, if you appeal an appellate court decision, your case may be heard at the highest level court—in California, it’s the California Supreme Court; federally, it’s the United States Supreme Court. As a brief side note, New York names its courts differently—their trial level courts are called the Supreme Courts and their highest court is called the New York Court of Appeals. Go figure.
Judges - Local judges are elected public officials that serve terms whereas federal judges are appointed by the President with the consent of the Senate for life. What you need to know about trial court judges: In jury trials, the judge essentially acts as the referee—he or she decides on all legal issues, such as which evidence is to be admitted versus excluded and which lawyer objections to sustain (agree with) or overrule (disagree with). By contrast, the jury alone decides the factual issues. A main issue of fact, for example, would be whether the defendant committed the offense. A lot of people believe their fate rests in the hands of the judge. But, unless you chose to have a “court trial” where the judge alone decides everything and there's no jury involved, then that’s simply not the case. But in a jury trial, it’s really the jury, not the judge, that holds the power to convict or acquit you. However, if convicted, the judge will decide your punishment.
“Plaintiffs” vs “Defendants” - The plaintiff is the party who’s responsible for bringing forward the case. In civil cases, the plaintiff is the party that filed the lawsuit. In criminal cases, the plaintiff, generally, is the DA who filed criminal charges. The defendant, is the party that is forced to answer to either the lawsuit or criminal charges.
Here’s a fun fact: In a courtroom, the plaintiff’s table is always closest to the jury box. In other words, the criminal defendant sits furthest away from the jury. I believe this practice (though I'm admittedly speculating) developed from concerns about juror safety and to minimize the potential effect of juror intimidation by criminal defendants sitting nearby.
Other People in Court - In addition to the judge, every courtroom will have a bailiff, court clerk, and court reporter. The bailiff is generally a sheriff’s deputy assigned to keep order in the courtroom and protect the judge. The court clerk is in charge of all administrative duties. Lastly, the court reporter is the unsung hero of the courtroom who writes down all that is said in court verbatim, which is incredibly impressive and amazes me daily.
There you have it—the players in the criminal justice system of which, as you can see, there are many. I didn't include everyone, of course, but hopefully this post helps you to understand or at least know who's who whether you're caught up in a real-life criminal case or a TV drama depicting one.