California takes the strictest line on unknown claims. Omit the §1542 waiver and a court may later allow a claim the releasing party did not know about at signature, defeating the purpose of buying peace. Where litigation is pending, the parties must ask the court to retain jurisdiction under Code Civ. Proc. §664.6 while the case is still open. Mediated settlements face a further wrinkle: under Evid. Code §1123, the agreement stays inadmissible unless it states that it is binding, enforceable or admissible.
New York enforces written releases without consideration under Gen. Oblig. Law §5-1103, an unusual rule that makes release scope drafting more important than elsewhere. In a settled damages action, CPLR 5003-a gives the settling defendant 21 days to pay after tender of the executed release and stipulation of discontinuance, or 90 days for a municipality, and an unpaid plaintiff can enter judgment without further notice. Releasing one of several tortfeasors does not discharge the others unless the release says so, under Gen. Oblig. Law §15-108.
Texas treats a mediated settlement as an enforceable written contract under Civ. Prac. & Rem. Code §154.071, and breach of the settlement itself is a four year action under Civ. Prac. & Rem. Code §16.004.
Florida voids confidentiality in one often overlooked case. Under the Sunshine in Litigation Act, Fla. Stat. §69.081, any part of an agreement whose purpose or effect is to conceal a public hazard is unenforceable, and news organizations have standing to challenge it. Never accept a confidentiality clause covering a product that has injured someone in Florida. Release of one tortfeasor also leaves the others exposed under Fla. Stat. §768.041.