Resisting unlawful arrest is a possible justification

Excuse

In jurisprudence, an excuse or justification is a defense to criminal charges that is distinct from an exculpation. In this context, "to excuse" means to grant or obtain an exemption for a group of persons sharing a common characteristic from a potential liability. "To justify" as in justifiable...

 for breaking the law

Law

Law is a system of rules and guidelines which are enforced through social institutions to govern behavior, wherever possible. It shapes politics, economics and society in numerous ways and serves as a social mediator of relations between people. Contract law regulates everything from buying a bus...

. Defendant

Defendant

A defendant or defender is any party who is required to answer the complaint of a plaintiff or pursuer in a civil lawsuit before a court, or any party who has been formally charged or accused of violating a criminal statute...

s who use this defense

Defense (legal)

In civil proceedings and criminal prosecutions under the common law, a defendant may raise a defense in an attempt to avoid criminal or civil liability...

 are arguing that they should not be held guilty for a crime

Crime

Crime is the breach of rules or laws for which some governing authority can ultimately prescribe a conviction...

, since the actions taken were intended to protect them from an unlawful arrest

Arrest

An arrest is the act of depriving a person of his or her liberty usually in relation to the purported investigation and prevention of crime and presenting into the criminal justice system or harm to oneself or others...

.
Many courts will not tolerate any violence

Violence

Violence is the use of physical force to apply a state to others contrary to their wishes. violence, while often a stand-alone issue, is often the culmination of other kinds of conflict, e.g...

 whatsoever (committed while resisting an unlawful arrest), and almost certainly not "deadly force," unless the police

Police

The police is a personification of the state designated to put in practice the enforced law, protect property and reduce civil disorder in civilian matters. Their powers include the legitimized use of force...

 began to use violence before the defendant began to do so. In short, a defendant might be justified in running away from police attempting an unlawful arrest; but, almost certainly will not be considered justified in shooting

Shooting

Shooting is the act or process of firing rifles, shotguns or other projectile weapons such as bows or crossbows. Even the firing of artillery, rockets and missiles can be called shooting. A person who specializes in shooting is a marksman...

 police who attempt to do so (unless the defendant can somehow prove

Evidence (law)

The law of evidence encompasses the rules and legal principles that govern the proof of facts in a legal proceeding. These rules determine what evidence can be considered by the trier of fact in reaching its decision and, sometimes, the weight that may be given to that evidence...

 self-defense

Self-defense (theory)

The right of self-defense is the right for civilians acting on their own behalf to engage in violence for the sake of defending one's own life or the lives of others, including the use of deadly force.- Theory :The...

).
Many states such as Illinois

Illinois

Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...

have clauses in the law to prevent any legal justification of resisting an unlawful arrest.