A more thorough explanation:

Wharton's rule is a legal doctrine that states that an agreement by two or more people to commit a particular crime cannot be prosecuted as a conspiracy if the crime could not be committed except by the actual number of participants involved. However, if an additional person participates to enlarge the scope of the agreement, all the actors may be charged with conspiracy.

For example, if two people plan to rob a bank and the robbery requires only two people, they cannot be charged with conspiracy. But if a third person joins the plan to help them rob the bank, then all three can be charged with conspiracy.

The rule is named after Francis Wharton, an influential criminal-law author. It is also known as the Wharton rule or concert-of-action rule.

It is important to note that Wharton's Rule only applies to offenses that require concerted criminal activity, meaning that multiple people are needed to commit the crime. In such cases, the rule helps determine whether the conspiracy and the substantive offense should be considered separate crimes or merge into one.

Overall, Wharton's Rule is an aid to the determination of legislative intent and must defer to a discernible legislative judgment.