The U.S. Supreme Court on Tuesday declined to hear a challenge to California's worker misclassification law, letting stand a federal appeals court finding that state leaders had  rational reasons to target app-based ride and courier companies.

The high court denied a certiorari petition filed by Postmates, Uber Technologies and two drivers for the companies that argued California's AB 5 unfairly singled out app-based platforms for strict regulations determining who can be deemed an independent contractor. The decision lets stand a June ruling by the U.S. Court of Appeals for the Ninth Circuit that the law does not violate state and federal equal protection clauses.