## Facts

- Riverside County routinely made arrests without warrants and deferred the judicial probable-cause determination until arraignment.
- County policy provided for arraignment “within two days of arrest, excluding weekends and holidays,” which often resulted in detention beyond 48 hours before any judicial probable-cause determination.
- Warrantless arrestees filed a § 1983 class action seeking declaratory and injunctive relief, alleging unlawful delay under the Fourth Amendment.
- The district court certified a class and issued a preliminary injunction requiring probable-cause determinations within 36 hours absent exigent circumstances.
- The Ninth Circuit rejected standing objections and affirmed on the merits, concluding administrative steps incident to arrest required no more than 36 hours.
- The Supreme Court granted review.

## Issues

1. Whether the named plaintiffs and certified class had Article III standing and whether mootness barred adjudication when some individual claims ended before final judgment.
2. What temporal standard satisfies the Fourth Amendment requirement of a “prompt judicial determination of probable cause” following a warrantless arrest.
3. Whether a jurisdiction may exclude weekends and holidays, or otherwise tie probable-cause determinations to arraignment, in a way that commonly extends detention beyond 48 hours.

## Decision

- The Court held Article III was satisfied; although some named plaintiffs’ claims became moot, the claims were inherently transitory and could proceed through class certification using relation-back principles.
- The Court rejected a fixed 36-hour constitutional limit as an across-the-board rule.
- The Court held that, as a general matter, a probable-cause determination within 48 hours complies with the promptness requirement.
- The Court held that delays beyond 48 hours are presumptively unreasonable; the government bears the burden to show a bona fide emergency or other extraordinary circumstance.
- The Court held that intervening weekends and holidays are not extraordinary circumstances and do not justify exceeding 48 hours.
- The judgment was affirmed in part and reversed in part: the county’s practice was unconstitutional to the extent it permitted routine delays beyond 48 hours without extraordinary justification.

## Legal Principles

- A warrantless arrestee must receive a prompt judicial probable-cause determination as a prerequisite to extended restraint of liberty.
- A probable-cause determination within 48 hours of a warrantless arrest is generally timely, but the detainee may still show unreasonableness within 48 hours (e.g., delay to gather evidence, ill will, or delay for its own sake).
- If the determination occurs more than 48 hours after arrest, the delay is presumptively unreasonable and the government must prove a bona fide emergency or other extraordinary circumstance.
- Routine administrative convenience, including combining probable-cause review with arraignment and excluding weekends or holidays, does not constitute an extraordinary circumstance.
- For class actions challenging short-duration detention practices, claims may proceed despite mootness of individual claims when the controversy is inherently transitory and class certification relates back.

## Conclusion

The Court clarified that the Fourth Amendment generally requires a judicial probable-cause determination within 48 hours after a warrantless arrest, treats delays beyond 48 hours as presumptively unlawful absent extraordinary justification, and allowed class-wide injunctive litigation to continue despite the rapid mootness of individual detention claims.


County of Riverside v. McLaughlin, 500 U.S. 44 (1991)