As a consequence of the result of the December 2016 constitutional referendum, in which the Senate reform was rejected, the two chambers of the Italian Parliament ended up with two different electoral laws, which lacked uniformity. As a matter of fact, the electoral law for the Chamber of Deputies passed by Matteo Renzi's government, the so-called "Italicum", based on a strong winner-take-all principle, was still in effect, whereas in the Senate a pure proportional system (the remnants of the so-called "Porcellum", the electoral law approved by the cabinet of Silvio Berlusconi in 2005 and then declared extensively unconstitutional by the Constitutional Court in January 2014) was in force. The two systems differed on several aspects, among which the possibility of forming coalitions before the elections (only allowed at the Senate) and the election thresholds.