AUGUSTO PINOCHET was never fond of democracy. In 1990, at the end of his 17-year dictatorship, he engineered a stifling electoral system. It made voter-registration voluntary, but voting mandatory for those on the rolls, so that anyone who chose to sign up could be fined for not voting. Many Chileans duly failed to register oakley sunglasses, and turnout fell. Whereas 30% of the population voted for the winner of the 1989 presidential election, just 21% plumped for the victorious Sebastián Piñera in 2010.

Chile’s method for choosing Congress is poorly conceived as well. By electing the top two finishers in each district, its practical effect is that the two main coalitions take nearly all the seats. Chile is the only country in the world to use this “binomial” system.

Pinochet’s electoral legacy has proved remarkably durable. Conservatives have long fended off changes to the registration rules, which would make the electorate younger and poorer. And neither coalition wants to scrap two-member constituencies, a change which would threaten their legislative duopoly.

This system has brought stability, but at the cost of representation. Now Chileans have found new ways to show discontent. Last year saw a big demonstration against a dam in Patagonian wilderness, and months of huge protests by students demanding fully taxpayer-funded education. Mr Piñera’s approval rating fell to 36%.

In response, the president has started to open up politics. Last month he signed a law automatically registering all Chileans over 18 to vote. It will increase the size of the electorate by 55%, and triple the number of voters under 30. Younger voters might be expected to be preponderantly left-of-centre, but Mr Piñera seems to hope that they will thank him for bringing them into the process.

Changing the binomial system is harder. Everyone agrees that it limits political dynamism. “When you vote in Chile you’re offered red wine or white wine and that’s it fake oakleys,” says Ricardo Lagos, a former president. “There are no subtleties. You don’t get to choose a cabernet sauvignon, a merlot or a sauvignon blanc.”

Yet there is no consensus on what Chile should have instead. So last month congressmen from Mr Piñera’s party joined the opposition Christian Democrats in changing the subject: they proposed a semi-parliamentary system, in which the president would choose a prime minister, as happens in Peru. But Mr Piñera dismissed it, saying that Chile had “other more urgent priorities”.