California's Unfair Competition Law Can Help Workers Collect Unpaid Wages. Code § 17000, et seq. The.UCL generally prohibits any unlawful, unfair, or fraudulent business act or practice, as well as deceptive or misleading advertising. "unlawful, unfair or fraudulent" conduct in connection with virtually any type of business activity.2. In California, plaintiffs' lawyers and state and local prosecutors wield two powerful tools: the. California has an unfair competition law that prohibits unfair, deceptive, or fraudulent business practices or misleading advertising. Action under State Unfair or Deceptive Trade Practices Law. The Unfair Competition Law of California prohibits false advertising and illegal business practices. The UCL forbids "unlawful, unfair or fraudulent" conduct in connection with virtually any type of business activity. FTC to protect consumers from unfair and deceptive trade practices.