Gravamen

The term Gravamen refers to the most important part of a lawsuit. A typical way of using the word Gravamen would be as follows: The gravamen of a personal injury case involving a car crash might be the alleged drunk driving of the defendant.

Additional Sources

Answers.com

The part of a charge or an accusation that weighs most substantially against the accused.

Duhaime Legal Dictionary

The material part or essence of a charge, grievance or complaint.

Law.com Dictionary

n. Latin for "to weigh down," the basic gist of every claim (cause of action) or charge in a complaint filed to begin a lawsuit. Example: in an accident case, the gravamen may be the negligence of the defendant, and in a contract case, it may be the breach of the defendant.

The Free (Legal) Dictionary

n. the basic gist of every claim (cause of action) or charge in a complaint, particularly the failure to perform. Example: in an accident case, the gravamen may be the negligence of the defendant, and in a contract case, it may be the breach of the defendant.

Wikipedia

Gravamen (from Lat. gravare, to weigh down; gravis, heavy), (plural gra·va·mens or gra·vam·i·na), a complaint or grievance, the ground of a legal action, and particularly the more serious part of a charge against an accused person. In legal terms, the essential element of a lawsuit.

In English the term is used chiefly in legal submissions and judicial opinions. The word is commonly misspelled gravaman.

Apart from the normal usage of the word, the gravamen test is used in contract law to distinguish between the sale of goods and services in "hybrid" transactions. Under the test each component of the sale is isolated and individually determined to be either a good or a service. The more common approach used by courts is the predominant purpose test which looks at the general thrust of the exchange rather than each individual component.

The term is also used in ecclesiastical cases, being the technical designation of a memorial presented from the Lower to the Upper House of Convocation, setting forth grievances to be redressed, or calling attention to breaches in church discipline.