Regulators and the world's $700 trillion derivatives industry are closely watching a legal battle that began in Britain ... and which will fuel a sea change in swaps payouts. Four cases, including one involving a unit of collapsed U.S. bank Lehman Brothers, are being presented in a five-day hearing at the UK Court of Appeal. All revolve around payouts under the derivatives industry's master agreement", a framework contract. A bank that trades swaps with another bank typically has one master agreement which sets the terms for millions of transactions between them. The master agreement ... covers around 90 percent of off-exchange derivatives transactions. Under the agreement, Lehman's bankruptcy is considered a default. However, in the four cases before the court this week, the other party in the contracts elected not to terminate them because they would have had to pay out to the defunct bank.