You are required to help the police

or you will go to jail.

How is that? A man named Devonte Conerly who was suspected in a hit and run incident, and was allegedly tried to disarm the police officer who was attempting to arrest him. The police officer asked the crowd nearby to help him, and no in the crowd did anything to intervene. Officers responding to the original officer's call for help eventually subdued and handcuffed Conerly.

What did they do next? They threatened the members of the crowd with arrest under section 13A of Alabama's legal code, which reads:

(a) A person commits the crime of refusing to aid a peace officer if, upon command by a peace officer identified to him as such, he fails or refuses to aid such peace officer in:
(1) Effecting or securing a lawful arrest; or
(2) Preventing the commission by another person of any offense.
(b) A person is not liable under this section if the failure or refusal to aid the officer was reasonable under the circumstances. The burden of injecting this issue is on the defendant, but this does not shift the burden of proof.
(c) Refusing to aid a peace officer is a Class C misdemeanor.

So you MUST, by law, assist any officer who asks for assistance. Even so, the Supreme Court has decreed that the police do not have to help YOU if you are asking. 44 of the 50 states have a similar statute.

Police have “no special duty” to aid a citizen facing an immediate lethal threat, according to the City Attorney of New York, in a successful bid to dismiss a lawsuit filed by Lozito. Lozito was nearly killed while subduing a spree killer named Maxim Gelman during a 2011 subway attack.

As Lozito placed Gelman in a chokehold, the maniac stabbed Lonzito in the head. Bleeding and struggling to retain consciousness, Lozito pleaded for help from NYPD Officer Terrance Howell, who was hiding behind a locked partition and refusing to get involved. It wasn't until AFTER Lozito managed to pin Gelman down and disarm him that Howell emerged from his secure location, officiously telling Lozito, “You can get up now.”

Howell did nothing to detain or subdue the murderer, but he was the one photographed triumphantly escorting Gelman away from the scene in handcuffs, and was called a “hero cop” in the media. He later admitted to a member of a grand jury that he hid from the suspect out of fear for his safety -- and no moral or policy consideration is more important than the sacred principle of "officer safety."

Here is the rub: the police officer is protected by quallified immunity if it turns out that the arrest or the force used to affect it is unlawful. You do not.