Hansberry v. Lee, 311 U.S.32 (1940), is a famous case now usually known in civil procedure for teaching that res judicata may not bind a subsequent plaintiff who had no opportunity to be represented in the earlier civil action. The facts of the case dealt with a racially restrictive covenant that barred African Americans from purchasing or leasing land in a Chicago neighborhood. The covenant had been upheld in a prior class action lawsuit, which had included Lee, along with all the other neighborhood landowners, as members of the class. The defense in the present case argued that Hansberry could not contest the covenant because it had already been deemed valid by the courts in the prior lawsuit.
The US Supreme Court disagreed and held that since some of the neighborhood landowners (46%) comprising the class of the prior lawsuit did not support the restrictive covenant, the previous decision that the covenant was valid could not apply to all members of that class. In other words, it was erroneous to allow the 54% of neighborhood landowners who had supported the restrictive covenant to represent the interests of the 46% who were against it. Therefore, the Supreme Court held that the restrictive covenant could be contested in court again, even though some of the parties involved may have been included in the prior class of neighborhood landowner.