The everyday use of the word mayhem has evolved pretty far from its original, legal definition. In the legal context, "mayhem" doesn't denote a kind of rowdy disorder, but rather force causing serious and gruesome injury.
Mayhem is an old version of the word maim. The crime dates back several centuries to England. Originally, the crime of mayhem consisted of dismembering one of the king's subjects, rendering him unfit for battle. Today, statutes typically define the crime as disfiguring or disabling a victim. It's usually a grisly affair, often entailing injury to the face. Attacks that result in the loss of an eye, nose, or ear are common examples.
Some states incorporate mayhem into their assault and battery statutes and don't use the exact term "mayhem." Others, like California and Massachusetts, consider mayhem its own offense. Either way, "mayhem" in the criminal law context typically means a brutal assault and battery that leads to a serious injury. (Of course, as with other violent crimes, an affirmative defense like self-defense may apply, depending on the facts).
Mayhem is a serious crime, and defendants may face long prison terms and, where the crime is aggravated mayhem, even life in prison.
The requirements for mayhem depend on the jurisdiction. In some states, use of illegal force resulting in a disfiguring or disabling injury is enough. In other states, a defendant must also have acted maliciously, intending to injure the victim, for a mayhem conviction.
Aggravated mayhem is a more serious form of mayhem that usually involves the defendant intending to permanently maim the victim, rather than simply injure him or her.
For the crime of mayhem to be complete, there must be an injury. So, wanting and attempting to take someone's eye out aren't enough. That said, a failed attempt will still be enough for conviction of another crime, like attempted mayhem or something within the assault-and-battery spectrum.
The injuries for mayhem have to be permanent or at least last for a significant period of time; a bad injury that will heal in a matter of weeks or months may not suffice. In addition to facial injuries, injuries that result in restricted movement or reduced mental capacity are enough for a mayhem conviction.
For an injury to lead to a mayhem conviction, it must be physical, rather than emotional: Severe mental anguish or psychic injury isn't enough. In addition, the victim must be alive at the time of the maiming. (Disfigurement of a corpse may be its own offense, but it doesn't constitute mayhem.)
Convictions for mayhem often involve horrific acts that result in devastating injuries. Your typical fistfight won't qualify. But when injuries are more severe than a black eye and move into the permanent realm, like loss of a limb or appendage, then mayhem may be in play.
In one case, an appellate court upheld the defendant's conviction for malicious disfigurement after he beat a woman and burned her with an iron, leaving a permanent scar. (Hudson v. U.S., 790 A.2d 531 (D.C. 2002).) Other examples of mayhem include inflicting lasting brain damage from bashing someone in the head, and unlicensed practice of medicine that leads to permanent injury for the patient.
If you've been charged with mayhem or any other crime, consult an experienced criminal defense attorney. Only such a lawyer can fully advise you of the applicable law, including the potential sentence. That kind of lawyer can also analyze your options and protect your rights.