Hansberry v. Lee, 311 U.S. 32 (1940), is a famous and commonly-used case in civil procedure classes in the United States for teaching that res judicata does not apply to an individual whose interests were not adequately represented in a prior class action.

[1] The facts of the case dealt with a racially-restrictive covenant, which barred African Americans from purchasing or leasing land in the Washington Park Subdivision of Chicago's Woodlawn neighborhood.

Anna M. Lee, a homeowner, sought to enforce the racially restrictive covenant and void the sale.

The Court explained: Those who sought to secure [the covenant's] benefits by enforcing it could not be said to be in the same class with or represent those whose interest was in resisting performance, for the agreement, by its terms, imposes obligations and confers rights on the owner of each plot of land who signs it.

If those who thus seek to secure the benefits of the agreement were rightly regarded by the state Supreme Court as constituting a class, it is evident that those signers or their successors who are interested in challenging the validity of the agreement and resisting its performance are not of the same class in the sense that their interests are identical...Without a sufficiently identical interest, the Court held that the interests of the class members could not have been adequately represented and that binding them to a judgment in a case in which they were not adequately represented would violate their due process rights.