DOUGLAS, Isle of Man — The Isle of Man’s governing body, the Tynwald, was founded by Viking settlers and first gained notoriety in 1237 when a gathering degenerated into a pitched battle between two factions that left three men dead.

These days, disputes are settled peaceably at the ballot box, and there is no real party system in the Tynwald, which some citizens see as a modern form of Athenian democracy. Still, much is at stake in elections on Thursday.

Situated in the Irish Sea, the Isle of Man is a geopolitical oddity: It is not technically part of the United Kingdom but is instead a crown dependency. Queen Elizabeth II is the head of state, yet the island is self-governing and reliant on Britain for its defense. It is not a member of the European Union, but its close ties to Britain mean that it effectively trades under Europe’s system of tariffs and customs duties.

In recent decades, that system has suited the Isle of Man just fine. It has chalked up more than three consecutive decades of annual economic growth. It has kept business taxes low or at zero, while bringing more transparency to its banking system in an effort to shed its reputation as a tax haven. It has nurtured online gambling and other new niche industries.