When someone is arrested, the police often charge the individual with resisting arrest in addition to the underlying arrest charge. It takes little to prove a resisting arrest charge. If an individual is lawfully arrested, any intentional act which serves to obstruct or prevent that arrest will suffice. This can be something as little as raising one's arms when the police officer is trying to put on handcuffs. Usually, a resisting arrest case turns on whether the underlying arrest was “authorized.” If a police officer arrests an individual without reasonable cause, then the arrest is not authorized, and and there can be no proper charge of resisting arrest.
Even if someone is arrested unlawfully, he or she does not have the right to forcibly resist a police officer. A person who forcibly resists an unlawful arrest by a police officer can be charged with assault, since the unlawfulness of the arrest is not considered to be justification for violently resisting.
No one should forcibly resist any arrest, whether the arrest is lawful or not. If you find yourself in a situation where you are being arrested by a police officer, even if the officer is making a mistake, the smart thing to do is to cooperate, remain calm, and ask for an attorney. If you have been arrested without good cause, you may be able to file a lawsuit for unlawful arrest. If the officer is arresting you with good cause, resisting that arrest will only add to your legal troubles and make a successful resolution of your criminal case, either by way of trial or plea bargain, more difficult.
Notwithstanding the above, in light of recent events including the disgraceful killing of George Floyd, it is important to emphasize that nobody ever forfeits their right to defend themselves against violence. Lawful and even unlawful arrests should not be physically resisted, but the law still recognizes the right to defend oneself, even against police officers.