Yes, spoilers in the links are intended to save me the trouble of arbitrating.
I forgot about the tulips. The PDF is titled "Private Ordering at the World's First Futures Exchange" but maybe it should be qualified as the first semi-legally-recognized one.
Despite the shogunate's relative laxity, Dojima participants nevertheless acted in the long shadow of latent governmental regulation. Licensing requirements determined the players of the game. The monopoly on futures contracts granted to Dojima likely increased the force of internal sanctions. The threat of license confiscation may have created additional incentives for proper behavior. The Dojima experience thus leaves open the possibility that the development of efficient rules in self-organized markets may require something less than complete governmental withdrawal.
Regulatory developments at Dojima, especially before 1730, bear striking resemblance to those in early European and American markets. In the famous seventeenth-century Dutch tulip forwards market, trading persisted despite six government attempts to ban such trading. In England, the passage in 1734 of Sir John Barnard's Act, "[a]n act to prevent the infamous practice of stock-jobbing," effectively banned the trading of options. Yet despite fines for selling stock that one does not own, option transactions apparently continued. In New York, a 1792 law, the "watered-down equivalent of Barnard's Act," did not explicitly prohibit options transactions, but made options contracts void and thus unenforceable in court. In New York as in England, "time bargains went on as before, but were enforced privately, without the assistance of the legal system."