A misdemeanor (American English, spelled misdemeanour in British English) is any “lesser” criminal act in some common law legal systems. Misdemeanors are generally punished less severely than felonies, but theoretically more so than administrative infractions (also known as minor, petty, or summary offences) and regulatory offences. Many misdemeanors are punished with monetary fines.
A misdemeanor is considered a crime of low seriousness, and a felony one of high seriousness. A principle of the rationale for the degree of punishment meted out is that the punishment should fit the crime. One standard for measurement is the degree to which a crime affects others or society. Measurements of the degree of seriousness of a crime have been developed.
In the United States, the federal government generally considers a crime punishable with incarceration for one year or less to be a misdemeanor. All other crimes are considered felonies. Many states also employ the same or a similar distinction.
The distinction between felonies and misdemeanors has been abolished by several common law jurisdictions (notably the UK and Australia). These jurisdictions have generally adopted some other classification (in the UK the substance of the original distinction remains, only slightly altered): in the Commonwealth nations of Australia, Canada, New Zealand, and the United Kingdom, the crimes are divided into summary offences and indictable offences. The Republic of Ireland, a former member of the Commonwealth, also uses these divisions.