Williams v. Illinois, 399 U.S. 235 (1970), was a United States Supreme Court case in which the Court held that, if a person cannot afford to pay a fine, it violates the Equal Protection Clause to convert that unpaid fine into jail time to extend a person's incarceration beyond a statutory maximum length.

[1] The syllabus of the case stated: Appellant was given the maximum sentence for petty theft under Illinois law of one year' imprisonment and a $500 fine, plus $5 in court costs.

The judgment, as permitted by statute, provided that, if, when the one-year sentence expired, he did not pay the monetary obligation, he had to remain in jail to work them off at the rate of $5 a day.

Held: Though a State has considerable latitude in fixing the punishment for state crime, and may impose alternative sanction, it may not, under the Equal Protection Clause, subject a certain class of convicted defendants to a period of Imprisonment beyond the statutory maximum solely by reason of their indigency.

41 Ill. 2d 511, 244 N.E.2d 197, vacated and remanded.A companion case, Morris v. Schoonfield,[2] was "remanded for reconsideration in light of intervening Maryland legislation and decision in Williams".