Accomplice Liability and Parties to Crime

The common law drew sharp lines among parties to a felony. The principal in the first degree actually committed the crime. The principal in the second degree was present (actually or constructively) and aided or encouraged — the getaway driver waiting outside, or the lookout. The accessory before the fact aided or encouraged but was not present at the scene — the person who supplied the gun and the plan but stayed home. The accessory after the fact gave aid after the felony was complete, knowing of it, to help the felon escape justice.

These distinctions mattered procedurally: at common law an accessory could not be convicted before the principal, and a defect in charging the principal could free the accessory. Modern jurisdictions abolish the distinction among the first three categories. Today the principal is the one who, with the required mens rea, commits the act; everyone else who aids, abets, counsels, or encourages with intent is an accomplice and is liable to the same extent as the principal — convicted of the substantive offense itself. The accessory after the fact remains a distinct and far less serious offense.

To be an accomplice the defendant must (1) provide assistance or encouragement and (2) do so with the intent (or, in some jurisdictions, knowledge) that the principal commit the crime. The aid can be trivial — a word of encouragement, acting as a lookout, providing a tool — and need not be a but-for cause; even encouragement that the principal did not rely on suffices. But the mental element is demanding. Mere presence at the crime scene, even presence combined with knowledge that a crime is occurring and silent approval, is not enough. The classic trap: D watches a friend shoplift and says nothing — D is not an accomplice.

Contrast: D positions himself by the door to warn of approaching staff — now D is a lookout and an accomplice. Two persons cannot be convicted of a crime that by definition requires only one perpetrator if one is the necessary victim (Wharton's Rule context). Note also that a person who could not commit the substantive crime as a principal (e.g., due to a protected-class statute) generally cannot be convicted as an accomplice to it where the statute was meant to protect that class.

The scope rule is heavily tested. An accomplice is guilty of the crime he intended to assist and of any additional crimes that are a natural and probable (foreseeable) consequence of that crime. If D drives the getaway car for an armed robbery and the principal shoots a resisting clerk, D is liable for the robbery and for the killing, because a killing is a foreseeable consequence of armed robbery.

California follows this 'natural and probable consequences' doctrine but has narrowed it dramatically for murder: under Senate Bill 1437 (effective 2019), a person can no longer be convicted of murder under the natural-and-probable-consequences theory; the prosecution must prove the accomplice acted with malice or was a major participant who acted with reckless indifference to human life (this is covered in the homicide and felony-murder sections).

Withdrawal terminates accomplice liability if it occurs before the crime is committed and is effective: an encourager must communicate a repudiation; an aider must do everything possible to neutralize the assistance (retrieve the tool, undo the act) or give timely notice to law enforcement. A mere change of heart that is not communicated or made effective is not a withdrawal.

The accessory after the fact stands apart from accomplice liability and is tested as its own offense. Its elements are (1) a completed felony by the principal, (2) the accessory's knowledge that the felony was committed, and (3) the giving of assistance to the felon with the intent to help him avoid arrest, trial, or punishment. Because the felony is already complete, the accessory is not liable for the underlying crime; instead, California charges this conduct under Penal Code section 32 as a distinct, lesser offense punishable as a wobbler.

A spouse who hides a fleeing felon is not exempt under modern California law, though jurisdictions vary. Distinguish the related but separate crimes of obstruction of justice and harboring. A recurring trap pairs the accessory-after-the-fact question with a failure-to-report fact pattern: merely failing to report a known felony (misprision at common law) is generally not a crime today and never makes one an accomplice; affirmative aid to the felon is required. The mens rea standard for accomplices themselves generates another trap.

Most jurisdictions and California require true intent that the crime be committed, so a supplier who sells ordinary goods knowing they might be misused is usually not an accomplice absent a stake in the venture or intent to further it; mere knowledge of the buyer's plan is generally insufficient, although a few courts treat knowledge as enough for serious crimes. The MPC requires the purpose of promoting or facilitating the offense, aligning with the intent approach.

California's most consequential modern reform reshapes the natural-and-probable-consequences doctrine for homicide: Senate Bill 1437 (2019), codified in Penal Code sections 188 and 189, abolished the natural-and-probable-consequences theory and the old felony-murder rule as bases for convicting an aider and abettor of murder. After SB 1437 an accomplice can be convicted of murder only if he acted with the intent to kill (express or implied malice as a direct aider and abettor) or was a major participant in an underlying felony who acted with reckless indifference to human life under the Banks and Clark standard.

The 2021 amendment in Senate Bill 775 extended the same relief to attempted murder and to manslaughter convictions obtained on the abolished theories, and created a resentencing petition process. A final trap: the natural-and-probable-consequences doctrine survives in California for non-homicide target crimes, so an accomplice to a robbery can still be liable for a foreseeable assault even though that same theory can no longer reach murder. Always separate the target crime, the foreseeable additional crimes, and — if a death occurred — the SB 1437 overlay before assigning accomplice liability.

Parties to Crime: Common Law vs. Modern