There are many branches of law in the United States. For instance, civil law is the law as it pertains to personal relationships, unions such as marriage, and interpersonal situations such as personal injury cases. Criminal Law is the branch of law that seeks to define crimes - what a crime is, who the victim is, and who the perpetrator is. Criminal law can be divided into two sections, each section involving specialized lawyers, criminal defense lawyers. The first type of criminal law is criminal procedure. This subsection of criminal law defines how trials are to be conducted. Criminal procedure law dictates how claims are to be investigated and outlines how evidence must be collected.

Criminal procedure aims to maintain an orderly legal system that is most effective in the pursuit of justice in light of the truth. Criminal Defense attorneys who specialize in criminal procedure are very careful to review how evidence is collected. They will be very specific in regards to their client's right and privileges under the law. A criminal defense attorney will ensure that the ideal of "innocent until proven guilty" is maintained through the investigation and presentation process.

The second type of criminal law is substantive. Substantive criminal law focuses on crime and punishment. Criminal Defense Attorneys involved in the substantive area of criminal law will be working with individuals accused of a crime. They will begin work when sought out by a client accused of a crime or appointed by the court, as in cases of financial need. Criminal defense attorneys will meet with clients and hear the details of events from their point of view. Everything shared between a client and his or her criminal defense attorney is confidential. A criminal defense attorney will not turn a client in if the client admits guilt, but will continue to help the client achieve success in the courtroom.

A good criminal defense attorney understands that everything is relative. The law is not black and white, but leaves a lot of gray room for interpretation. A criminal defense attorney will gather all of the facts of the case, both from the client and from the state or federal investigators. Armed with the facts, a criminal defense attorney will begin to build a case that presents the client in the best possible light. IF the client is guilty, the criminal defense attorney will try to present the facts of the case in such a way as to maintain a doubt of guilt. The jury, as the criminal defense attorney knows, is instructed that a person on trial must be proven guilty and does not need to be proven innocent. They will begin to comb through possible witnesses and will divide witnesses into character witnesses and witnesses to the actual events in question. A criminal defense attorney knows that character witnesses to present the person standing in trial in a good light will go a long way in the minds of jury members.

When a criminal defense attorney is defending a client, they will also seek to ensure the punishment fits the crime if their client is found guilty. A criminal defense attorney will utilize relativity to demand proportionality of punishment to crime in their client's best interest. A criminal defense attorney stands by their client until the trial's end, ensuring the outcome is as favorable as possible for their client