Type the name of the first plaintiff and first defendant, in that order, separated by a "v." for versus. Type a period. For example, if Jane Doe was suing John Smith, it would look like this: Doe v. Smith.
Insert "No." next followed by the number of the case or complaint in question. Follow this with another period. For instance, continuing with the above example, your citation should look something like this: Doe v. Smith. No. 123-456.
Place next the name of the court that decided the case. If the U.S. Supreme Court decided the Doe v. Smith case, it would look like this so far: Doe v. Smith. No. 123-456. Supreme Court of the US. (MLA style does not use periods in upper-case letter abbreviations.)
Type the date of the decision in standard MLA format. That is, the day number, space, the month, space and the year. End with a period. Continuing from above: Doe v. Smith. No. 123-456. Supreme Court of the US. 1 January 2011.
End your citation with the style of media from which you accessed the court decision followed by a period. If you found the court decision above in an official print reference from the Supreme Court, it would look like this, completed: Doe v. Smith. No. 123-456. Supreme Court of the US. 1 January 2011. Print.