Find the information needed: the name of the case, the place and year of the ruling, the federal supplement number and the complaint number.
Know your abbreviations. Abbreviate the court name and location. For example, if you are referencing a complaint from the State Department of New York, the abbreviation would be "S.D.N.Y." The other abbreviation to know is "F.Supp.," which stands for "Federal Supplement."
Cite the complaint in order as complaint, case name, federal supplement, court, date and filing number. For example: Complaint at 39, Peter v. Paul, 287 F. Supp. 78 (S.D.N.Y. 2003) (No. 98-2389).