It was enacted by the Tynwald, the island's legislature in 1874, stating that only water, malt, sugar and hops were allowed to be used in production.
[4] Because of the legal autonomy of the Isle of Man, the Free Mash Tun Act of 1880 which relaxed a tax on malt and other restrictions in the United Kingdom did not apply there, and so the act remained upheld.
[6] The current head of the Okells Brewery, Dr Mike Cowbourne, has stated that the law has been an important aspect of the company's beers achieving widespread export and acceptance.
[7][8] Okells used the changes in the law to produce a Canadian lager, which drew criticism from the local brewing community.
[10] In 2002, the Department of Health considered changing the law to allow the addition of Vitamin B1, which would help reduce alcohol induced brain damage.