The U.S. Supreme Court case Williams v. Illinois in 1969 dealt with the issue of extending a prison sentence beyond its maximum due to an inability to pay fines and court costs, which was challenged as violating the Equal Protection Clause of the Fourteenth Amendment. The petitioner, Willie E. Williams had been sentenced by an Illinois state court for petty theft and his term was extended because he could not afford to pay associated fines and costs totaling $425. In a 5-4 decision, however, the Supreme Court upheld this practice stating that it did not constitute "involuntary servitude". The majority opinion argued that states have legitimate interests in both punishing offenders and ensuring payment of fines or restitution; thus they can constitutionally extend sentences within limits when offenders are unable to pay immediately upon sentencing.

In the dissenting opinion for Williams v. Illinois, Justice Thurgood Marshall argued that extending a prison term because an individual cannot pay a fine is equivalent to creating a "modern form of debtors' prison." He believed this practice was unconstitutional as it violated the Equal Protection Clause of the Fourteenth Amendment. According to him, such punishment discriminates against individuals based on their financial status and unfairly penalizes those who are unable to pay fines due to poverty. The justice also pointed out that there were other ways for states to collect fines without resorting to imprisonment, making such practices unnecessary and unjustifiable in his view.