How do Brazil’s congressional races work?

On Sunday, October 7, Brazil’s electorate will go to the polls to choose the country’s next president and 27 state governors. With the unrivaled chaos of the executive race, it is often overlooked that Sunday will also see Brazil elect a new congressional lower house, as well as two-thirds of the Senate.

As we have seen in recent years, with the impeachment of former president Dilma Rousseff and the approval of controversial reforms, Brazil’s legislature is much more important than whoever sits in the president’s office in Brasilia. Nearly everything the government attempts to put into practice must first be passed by Congress, and this current crop of lawmakers is seen as being the most conservative since the military dictatorship. 

House seat distribution

Color code: red for leftist parties, blue for right-wing parties, gray for centrist parties.

When the Congress is thrust into the spotlight, as it was with the lower house during Dilma Rousseff’s impeachment, the Brazilian people get a brief glimpse of the band of ragtag politicians they helped elect. Invariably, the people don’t like what they see.

When Ms. Rousseff’s impeachment was voted on in the House, the Brazilian public watched in horror as their elected representatives spouted the most bizarre reasons to support the ousting...