Yes, you can be charged as an accomplice to an attempted crime, and under federal law you face the same charge and the same maximum sentence as the person who actually made the attempt. It does not matter that the crime was never completed, and it does not matter that you were not at the scene. What matters is whether the person you helped took a substantial step toward the offense, whether you knew what they were trying to do, and whether you intentionally helped them do it.
What a Prosecutor Has to Prove
Three elements have to line up. The principal, meaning the person you assisted, must have taken a substantial step toward the target crime. You must have known what the principal was trying to accomplish. And you must have intentionally helped or encouraged that effort with the purpose of making it succeed.
Federal law states the rule plainly: anyone who “aids, abets, counsels, commands, induces or procures” an offense is punishable as a principal.1Office of the Law Revision Counsel. 18 USC 2 – Principals When the offense charged is an attempt, that same language applies, and the helper is treated as though they personally made the attempt.
A simple example shows how the pieces fit. You give a friend detailed building plans for a jewelry store, knowing they intend to break in. Your friend is caught trying to disable the alarm. The friend is charged with attempted burglary because disabling an alarm is a substantial step. You are charged with the same offense as an accomplice, because you knowingly provided assistance with the purpose of helping the burglary happen. The burglary never occurred, and that is irrelevant.
When Does an Attempt Actually Begin
Your exposure as an accomplice depends on the principal getting far enough to qualify as an attempt in the first place. A criminal attempt requires two things: a specific intent to commit a particular crime, and conduct that goes beyond mere preparation.
Federal courts and most states use the “substantial step” test. The conduct must go beyond preparation and strongly confirm the person’s criminal purpose. Buying a ski mask is preparation. Buying a ski mask, obtaining a weapon, driving to the bank, and trying to pry open the door is a substantial step toward robbery. Staking out a target, assembling specialized tools, or luring an intended victim to a specific location can also qualify.
A minority of jurisdictions still use older “proximity” tests that require the defendant to come dangerously close to completing the crime. Under those tests, a plan caught early may not reach attempt at all. Under the substantial step test, it can.
The Two Layers of Intent
Charging someone as an accomplice to an attempt requires the prosecution to prove two separate mental states, and this is usually where cases are won or lost.
The first layer is that you intended to perform the act of assistance itself. Accidentally leaving a door unlocked is not the same as deliberately providing a key. The help has to be voluntary and purposeful.
The second layer is that you shared the principal’s intent for the crime to succeed. Lending someone a crowbar is not a crime. Lending someone a crowbar because you know they plan a break-in and you want it to happen is. Courts sometimes call this shared criminal purpose, and it is the most contested element at trial because the jury has to infer it from circumstantial evidence.
The practical line sits between knowledge and purpose. In most jurisdictions, merely knowing your assistance might be used in a crime is not enough. The prosecution has to show you acted with the purpose of facilitating the criminal objective. A hardware store clerk who sells a crowbar to a suspicious customer has not committed a crime, even if the clerk suspects the buyer is up to something. A clerk who sells the same crowbar off the books, at a premium, because they know it is for a burglary, is in different territory.
What Counts as Helping
Assistance can be physical, financial, or purely advisory. Providing the plan, lending equipment, serving as a lookout, offering encouragement, or driving the getaway car can all make you an accomplice. You do not need to be at the scene.
What does not count is simply being there. Mere presence, even with knowledge that a crime is unfolding, is not enough to make you an accomplice. Standing in a parking lot while a friend shoplifts, without knowing about or encouraging the theft, creates no liability. The prosecution must show you actually did something to help or encourage the offense.
Backing Out: Withdrawal as a Defense
If you helped plan or prepare for a crime and then had a change of heart, withdrawal can defeat accomplice liability, but the requirements are strict. Deciding you no longer want to be involved is not enough.
If your involvement was limited to encouragement or verbal support, you generally need to clearly communicate to the principal that you are out, and you must do so before events become unstoppable. If you provided physical help like tools, plans, or money, a verbal renunciation will not cut it. You have to take affirmative steps to undo what you gave. That might mean retrieving the tools, warning law enforcement in time to intervene, or otherwise rendering your prior assistance ineffective.
The Model Penal Code frames this as an affirmative defense requiring a “complete and voluntary renunciation” of criminal purpose. The renunciation has to be genuine. Backing out because you got scared of getting caught, or because the target turned out harder than expected, does not qualify. Courts set the bar deliberately high because easy withdrawal would give accomplices a risk-free option during planning.
What You Are Facing
Under federal law, an accomplice faces the same punishment as the person who directly committed the offense.1Office of the Law Revision Counsel. 18 USC 2 – Principals When the offense is an attempt, both the principal and the accomplice face the penalty for the attempt itself, which is typically lower than for the completed crime.
The sentence is tied to the attempt, not the completed offense that never happened. If the principal is convicted of attempted bank robbery and faces up to 20 years, the accomplice who helped plan the failed robbery also faces up to 20 years. There is no discount for being one step removed. The person who drew the plans and the person who walked into the bank are equally culpable in the eyes of the law.
State penalties vary but follow the same structure: the accomplice is treated as a principal and sentenced on the attempt charge. Many states reduce the maximum for an attempt to a fraction of the completed offense, often one-half or one grade lower. Whatever that reduced penalty is, it applies equally to the accomplice.
Related Charges That Often Come Up
Conspiracy
Conspiracy is a separate charge that often arises from the same facts but is legally distinct. It requires an agreement between two or more people to commit an offense, plus at least one overt act in furtherance of that agreement.2Office of the Law Revision Counsel. 18 USC 371 – Conspiracy to Commit Offense or to Defraud United States The overt act does not have to be the crime itself and does not have to rise to a substantial step. Accomplice liability, by contrast, requires no agreement at all. You can spontaneously help someone and still be an accomplice.
Federal conspiracy carries a maximum of five years in prison unless the target offense is a misdemeanor, in which case the conspiracy penalty is capped at the misdemeanor’s maximum.2Office of the Law Revision Counsel. 18 USC 371 – Conspiracy to Commit Offense or to Defraud United States Accomplice liability for the substantive offense often carries heavier potential punishment, because the accomplice is punished as a principal.
Accessory After the Fact
Timing matters. An accomplice helps before or during the crime. An accessory after the fact helps afterward, typically by hiding the offender, destroying evidence, or interfering with law enforcement. Federal law caps the punishment for an accessory after the fact at half the maximum sentence the principal faces, or no more than 15 years if the principal’s crime carries life or death.3Office of the Law Revision Counsel. 18 USC 3 – Accessory After the Fact If you helped plan a robbery that was then attempted, you are an accomplice. If you only hid the would-be robber from police after the failed attempt, you are an accessory after the fact. The exposure is very different.
When the Crime Was Impossible to Complete
If the attempt failed because the crime could not have been completed, impossibility sometimes helps and sometimes does not. Factual impossibility, where some circumstance the principal did not know about made success impossible, is not a defense. If your friend tried to burglarize a jewelry store that had already moved its inventory, the attempt charge still stands, and so does your accomplice charge for helping.
Legal impossibility is a defense but a narrow one. It applies when the defendant believed their conduct was criminal, but what they tried to do was not actually illegal. If your friend tried to “steal” property that actually belonged to them, there is no crime to attempt, and no attempt for you to be an accomplice to. Prosecutors rarely bring charges for conduct that is not criminal in the first place, so this defense is seldom seen in practice.