The petition was filed by Gujarat Congress leader Pareshbhai Dhanani

The Supreme Court will tomorrow hear a petition by the Congress to hold simultaneous elections to two Rajya Sabha seats that have fallen vacant after BJP's Amit Shah and Smriti Irani moved to the Lok Sabha.

The Election Commission has fixed July 5 for the Rajya Sabha by-elections to the two seats. The petition was filed by the Leader of the Opposition in the Gujarat assembly, Pareshbhai Dhanani.

Congress spokesperson Abhishek Manu Singhvi has said holding the elections for the two seats separately would be against the rules. "This would be a mockery of our constitutional ethos. It would be completely contrary to conventions. Whenever there are two seats of a state going vacant, you have elections together. It is obvious to everybody that the purpose of that is to ensure there is a fair exercise of franchise of each MLA," Mr Singhvi said last week.

Amit Shah's Rajya Sabha seat was declared vacant on May 28 after he won his first Lok Sabha election from Gandhinagar in Gujarat in last month's election. Smriti Irani's seat was notified as vacant a day later; she defeated Congress president Rahul Gandhi in his constituency Amethi in Uttar Pradesh.

The notifications were separate because while Amit Shah, the BJP president and Union Home Minister, was declared winner on May 23, the day of the national election results, Smriti Irani's result was announced only the next day.

In his petition, Mr Dhanani said the election body's order should be declared as "unconstitutional, arbitrary, illegal, void ab initio" and it violated Article 14 of the Constitution. The Congress lawmaker alleged the Election Commission has "arbitrarily, malafidely, maliciously and under the diktats of the incumbent government" invoked its residuary powers under Article 324 of the Constitution and arbitrarily issued the June 15 press note.

Rubbishing the allegation, the BJP said the "Congress has become a lie-spreading machine". "They are misleading the people. By-polls for Rajya Sabha always takes place separately," a BJP leader said last week.

Election Commission officials well-versed with Rajya Sabha polls agreed that by-polls to Rajya Sabha seats are always held separately.

The BJP has 100 legislators in the Gujarat assembly and the Congress has 71.

Mr Singhvi said if the election to each seat is held on different days, the BJP will win both in the "first-past-the-post" system since it has 20 more lawmakers. If the voting is held simultaneously on the same day, the Congress can win one of the seats, he said. But these elections are never clubbed together, an election commission official pointed out.

Legislators vote in Rajya Sabha elections in what is called proportional representation with the single transferable vote system. Each lawmaker's vote is counted only once. The lawmakers list their order of preference for each candidate. The candidate that is the first choice for more voters, wins.