Hong Kong’s legislature approved the biggest overhaul of its political system in the quarter century since British rule on Thursday, in a decisive step to assert Beijing’s authority over the autonomous city. The changes will reduce the proportion of seats in the legislature that are filled by direct elections from half to less than a quarter. A new body will be empowered to vet candidates and bar those deemed insufficiently patriotic towards China from standing. “These 600-or-so pages of the legislation come down to just a few words: patriots ruling Hong Kong,” said Peter Shiu, a pro-Beijing lawmaker. Most of the changes were announced by China in March, though Hong Kong authorities later contributed further details, such as redrawing constituency boundaries and criminalising calls for bal...