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What is Criminal Law?

Throughout the United States, there are around 10.5 million arrests made each year. This means that an arrest occurs every three seconds–but are they all fair?

Thanks to the Sixth Amendment of the U.S. Constitution, criminal defendants have the right to be represented by a lawyer. If an accused person facing prison or jail time cannot afford a lawyer, the U.S. Constitution requires the state to provide legal representation for the accused party. 

Criminal events can be very intricate, especially concerning several charges and defendants. Anytime you are charged with criminal activity, it is in your best interest to hire a lawyer to protect your rights and ensure you receive fair treatment while building a strong defense. 

Criminal Law

For most people, familiarity with the criminal justice system comes from movies, TV shows, and books. Nevertheless, when personally involved with the criminal law system, real-life issues come into play, and the need for information and assistance can arise quickly. 

Criminal law is composed of issues that arise from criminal offenses. Criminal offenses are defined by federal, state, or local regulations ranging from serious criminal activity, such as murder, to minor infractions, such as running a red light. Within criminal law, there are criminal punishments, which are also established by statutory law, and are usually consistent with the severity of the crime. Minor offenses are only able to be punishable with fines or short-term probation. Depending on the conditions and jurisdiction, violent crimes can result in prison time, life sentences, and sometimes even a death sentence. 

A crime is an act or omission that establishes an offense that may be prosecuted by the state and is punishable by law. The majority of crimes are defined by statute and will vary across different states and counties. The Model Penal Code (MPC) provides a good overview of the most common types of crimes, while the U.S. Code provides a list of all federal crimes. Check your local penal code for a list of crimes in your state or local municipality.

To understand criminal law, there are a few terms that you should become familiar with:

  • Charge- A formal allegation of criminal actions
  • Indictment- A formal charge authorized by a grand jury
  • Arraignment- A pretrial proceeding in which an individual accused of committing a crime is brought into court, notified of their charges, and asked to plead guilty or not guilty 
  • Felony- A serious crime that is punishable by more than a year in prison
  • Misdemeanor- A criminal offense with a punishment less severe than a felony but typically punishable by less than a year in jail
  • Infraction- A minor offense or administrative violation typically punishable only by a fine 
  • Reasonable doubt-  A defendant can only be convicted if the jury believes the accused is guilty beyond a reasonable doubt; the highest burden of proof in the U.S. legal system
  • Plea bargain- The process by which a defendant and prosecutor negotiate a compromise; the defendant usually pleads guilty to one or more offenses in exchange for a lighter sentence or possible termination of other pending charges
  • Miranda rights- The legal rights that an arresting officer must offer a suspect before police question the suspect; these rights consist of the right to remain silent, to have a lawyer present during any/all police questioning, and to have a lawyer provided by the state at no expense if the suspect cannot afford one

The System and Procedure

The criminal justice system includes the entire criminal process–from the investigation and arrest to the conviction and sentencing– and each person that plays a role in the process. These can include law enforcement officers, prosecuting attorneys, bail bondsmen, criminal defense attorneys, judges, witnesses, probation officers, and corrections officers. 

During any phase of the criminal process, a person suspected of or charged with a crime is entitled to certain fundamental rights from the U.S. Constitution and other court decisions. These include the right to a lawyer and the right to a fast jury trial. These civil liberties balance the government’s goal of recognizing and punishing criminal behavior and the fundamental need to preserve and promote the individual freedoms that characterize a democratic society.

Prosecution of Crimes

While specific criminal acts vary by jurisdiction, they can be broadly characterized as felonies and misdemeanors. As outlined above, felonies include more violent crimes, like murder and rape, and are punishable by imprisonment of one year or more. Misdemeanors are not as severe and are punishable by less than a year of prison or fines. 

Unless a crime is a strict liability crime, meaning that no mental state is required, statutes typically break crimes into two separate elements: an act and a mental state. For instance, these components can be knowingly or recklessly. For a defendant to be convicted of a crime, a prosecutor must show that the defendant has met both of these elements. For example, larceny is the taking of another party’s property with the intent to deprive them of it permanently. With this example, if a defendant performed the act of taking the property and did so with the mental intention of taking another’s property, it would be feasible to prosecute the defendant for committing a crime. 

Nonetheless, if a prosecutor suggests that the defendant committed a crime but is not able to prove each element of the crime, that is not enough to charge a defendant. A prosecutor has to be able to prove each element of a crime beyond a reasonable doubt for a defendant to be convicted. Law enforcement officers, prosecutors, and other government officials must also follow certain criminal procedures when pursuing criminal activity. This is because all citizens have constitutional rights that the federal government must respect and protect. If these rights are not respected, it is possible to prevent a prosecutor from obtaining a conviction in a case. The U.S. Constitution sets forth these rights and protections offered to defendants. 

Common Criminal Defenses

When a defendant goes on trial for supposedly committing a crime, a prosecutor must establish that the defendant is guilty of a crime beyond a reasonable doubt. However, concurrently, the criminal defendant has the right to present a defense and can do so in numerous ways. Many criminal defenses are available within criminal law that allows defendants to avoid punishment for their actions. Some of the most common criminal defenses include:

State of Mind and Intent

One category of defense available to defendants is arguing that they cannot be found guilty because they were not aware of what they were doing or that their actions were wrong. At its most severe, this can include the defense of insanity. The defense of insanity requires the defendant to prove that they had a mental disorder that caused them to be incapable of understanding right from wrong or prevented them from controlling their actions and resisting violent impulses. In many states, the defense of insanity will keep defendants out of prison but require them to be held in a psychiatric facility for treatment.

Likewise, the defense of intoxication also relies on the theory that the defendant cannot meet all of the elements of the crime because they did not understand what they were doing. If the defendant was involuntarily intoxicated, this could be a defense to both the general and specific intent crimes under the theory that the intoxication prevented the defendant from understanding right from wrong. Voluntary intoxication is another defense, but only to specific intent crimes when the defendant argues that their intoxication prevented them from forming the intent necessary for the crime. 

Also, a criminal defendant can argue the mistake of law or fact. Under this defense, the defendant made a basic mistake that negates a component of the crime. For instance, a defendant charged with robbery can argue that he thought the victim had given him the property. Likewise, a mistake of law applies when a criminal defendant believes their actions were legal; however, this defense applies in few circumstances.


Another common defense category applies when the defendant committed the crime but argues that they were justified in doing so. Two of the most commonly recognized defenses under justification are self-defense and defense of others. A defendant can argue that he shot an intruder to defend themselves because the intruder threatened him with a violent weapon. Similarly, under the duress defense, the criminal defendant argues that they only committed the crime because they were forced to do so by another person. For instance, a criminal defendant can say that a co-defendant told him that the co-defendant would kill him if he didn’t commit the theft. Lastly, the criminal defendant can argue that they committed the crime to prevent more significant harm under a necessity defense. For example, the defendant may claim that they needed to steal a car to chase down another individual who was threatening them with an incendiary device. 

A similar defense is that of defense-of-property. The defense of property can arise where the defendant used force or violence to protect property, such as land or items, from damage or destruction. A limitation with the defense of property is the amount of force used to protect property can never be lethal. 

No Crime Occurred

Lastly, a smaller set of defenses can be used to argue that even though it may appear there was a crime, the defendant did not commit a criminal act. The defendant can claim that no crime occurred because of the defense of consent. For example, the defendant can argue that although sexual intercourse happened, it was not raping because there was consent. A criminal defendant can claim the defense of abandonment/withdrawal if they originally intended to commit or participate in a crime but changed their mind and withdrew from participation. Another possible argument could be entrapment. Entrapment can happen when the government convinces an individual to commit a crime and then attempts to punish the person for it. The defendant can argue that no crime would have occurred without the government's coercion, and they should not be held liable.

Steps in the Criminal Law Process

It is important to remember that not every criminal case will follow the same road. The steps in the criminal law process described below are not all-encompassing. Some cases can be straightforward and not involve every step, and others can be more complicated and involve most or all of the steps in the process. 

  • Investigation
  • Charging
  • Initial hearing/arraignment
  • Discovery
  • Plea bargaining
  • Preliminary Hearing
  • Pre-Trial Motions
  • Trial
  • Post-Trial Motions
  • Sentencing
  • Appeal


The federal government has agencies that employ criminal investigators to collect and provide information to U.S. Attorneys in corresponding districts. The investigators at these agencies will investigate the crime, obtain evidence, and help prosecutors grasp the case. During this step, prosecutors will look for two types of evidence: direct and circumstantial. Direct evidence is any evidence that supports the truth without any interference. For example, testimony from an eyewitness would be direct evidence because the person physically saw the crime. Circumstantial evidence is a statement(s) or information taken indirectly or not based on first-hand experience—for example, a testimony about something that happened before or after the crime occurred.  


After all of the evidence from investigators is collected, the prosecutor will decide if the case should be presented to a grand jury. When a person becomes indicted, they are given a formal notice that it is believed they committed a crime. The indictment is composed of basic information that informs the person of the charges against them. For potential felony charges, a prosecutor will present the evidence to an unbiased group of citizens called a grand jury. Witnesses can be called to testify, evidence is given to the grand jury, and a summary of the case is presented to the grand jury. The grand jury listens to the prosecutor and witnesses and then votes on if they believe that enough evidence exists to charge the person with a crime. They can decide not to charge the individual after receiving the evidence, leading to no indictment from the grand jury. If a defendant is charged, they can hire a lawyer of their choice or choose to be represented by a lawyer appointed by the government.

Initial Hearing/Arraignment 

After the individual is charged, either that same day or a day later, they will be brought before a magistrate judge for an initial hearing on their case. At this time, the defendant will be given their rights, learn more about the charges they are facing, be given a lawyer (or choose a lawyer), and the judge will decide if the defendant will be released or held in prison until the trial. Sometimes, the law allows the defendant to be released from jail before the trial if they meet bail. If the defendant does not post bail, the judge can demand that the defendant remains in the U.S. Marshals' custody pending trial. The defendant will also have to plead guilty or not guilty to the charges during this step.


Before the trial starts, a prosecutor must learn as much about the case as possible. During the discovery phase, the prosecutor will talk to witnesses, study the evidence, and anticipate any issues during trial. At the same time, the defense attorney will be preparing the same way. Both the defense attorney and prosecutor will call witnesses to testify. Prosecutors must also provide the defendant with copies of information and evidence that are intended to be used during the trial. This process is called discovery and continues from the time the case begins to the time of the actual trial.

Plea Bargaining

If the government believes they have a strong case, sometimes they will offer the defendant a plea deal to avoid a trial or reduce their exposure to a longer sentence. A defendant can only plead guilty if they committed the crime and admit it in an open court before a judge. After admitting to the crime, they can be “sentenced” by the judge presiding over the court (and only that judge). Sometimes the government will agree, as a part of the plea bargain, to not recommend an enhanced sentence, but ultimately it is left up to the judge to determine how the defendant will be punished. If a defendant pleads guilty, there will be no trial, but the next step is to prepare for a preliminary hearing.

Preliminary Hearing

An initial hearing will most times be held as soon as the defendant pleads not guilty. The prosecutor needs to show that enough proof exists to charge the defendant. Preliminary hearings are not always required, and the defendant can choose to waive them. The preliminary hearing is similar to a mini-hearing. The prosecution will introduce the evidence and call witnesses to testify, and the defense can cross-examine witnesses. However, the defense cannot object to using specific evidence. Evidence can be presented at the preliminary hearing that was not allowed to be shown to the jury at trial. The preliminary hearing will conclude with the judge scheduling a trial if they believe the defendant committed the crime, or they will dismiss the charges if they believe the defendant did not commit the crime.

Pre-Trial Motions

One of the very last steps before trial is for a prosecutor to answer or file motions. A motion can affect the trial, courtroom, defendants, evidence, or even testimonies. Only judges will decide the outcome of a motion. 


After a long preparation period, the prosecutor is ready for the trial. This is the process in which the facts of the case are presented to a jury, and they decide if the defendant is guilty or not guilty. During this period, witnesses testify and evidence is presented against the defendant. The defendant will also be able to present his side, with the help of a defense attorney, also using witnesses and evidence. The prosecutor and defense attorney must choose a selection of jurors for this case to listen to the facts of the case and decide if the defendant committed the crime. During the trial, each side will go over opening statements, witness examinations, objections, and closing arguments. Following the closing arguments, the judge will inform the jury of the appropriate law and what they must do to reach a verdict. After being charged, the jury will go into deliberation and, after agreeing on a verdict, will notify the judges, attorneys, and defendant in an open court.

Post-Trial Motions

If the defendant is found guilty and convicted of the crime, many motions can be filed after the trial. Those can include:

  • Motion for a new trial
  • Motion for judgment of acquittal
  • Motion to vacate, set aside, or correct a sentence


A couple of months after the defendant is found guilty; they will return to court to be sentenced. After receiving guidance from many sources, the judge will decide the defendant's sentence. The judge will consider any aggravating or mitigating factors, such as whether the defendant had committed the same crime before, whether the defendant seemed to regret the crime, and the nature of the crime itself.


If a defendant believes they were wrongfully convicted or the sentence was too cruel, they can appeal to the Circuit Court. An appeal is the opportunity to raise specific errors that may have occurred at trial. Appeals are often complex and can result in the case returning to trial. Even after a circuit court judge decides an appeal, a defendant can try to appeal that decision to the United States Supreme Court in Washington, D.C.

Criminal events can be very complex. If you have been charged with a crime, it is in your best interest to hire legal representation to help navigate you through this process.

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