In the case of Cabell v. Chavez-Salido, 1981, the U.S. Supreme Court ruled that it was constitutional for states to require United States citizenship as a condition of employment for certain public positions such as probation officers. The court held that while generally speaking, classifications based on alienage are subject to strict scrutiny under the Equal Protection Clause of the Fourteenth Amendment, exceptions can be made when it comes to positions related directly to democratic governance and policy-making processes. In this case, because probation officers have significant responsibilities in law enforcement and play an important role in administering justice within their communities - including discretionary powers over individuals' liberties - they fall within these exceptions where citizenship requirements may be justified.

In the dissenting opinion for Cabell v. Chavez-Salido, Justice Thurgood Marshall argued that the majority's decision to uphold a citizenship requirement for probation officers in Los Angeles County was inconsistent with previous rulings on similar cases. He contended that this ruling contradicted past decisions where such requirements were deemed unconstitutional when applied to public school teachers and police officers. Marshall believed there was no compelling state interest justifying treating probation officers differently from these other roles, as they all serve vital functions within society and should be equally accessible to qualified individuals regardless of their citizenship status. Furthermore, he expressed concern about potential discrimination against lawful permanent residents who are otherwise fully integrated into American society but may not have yet obtained U.S. citizenship.