The filing was submitted last week.

The court challenge makes the Attorney-General's Chambers the defendant. It is to make the AGC say why the count of five presidential terms starts with former president Wee Kim Wee instead of his successor Ong Teng Cheong, causing a reserved election to be triggered.

In a press conference Tan called in March this year, he said the upcoming presidential election should be open to candidates from all races, instead of a reserved election for candidates from the Malay community.

He had also voiced his concerns that "the changes were introduced to prevent my candidacy".

Parliament approved these changes to the elected presidency in November 2016, stating that if the president was not from one of its three main communities over the past five terms, the next election would be reserved for candidates from that community. This ensures the presidency reflects Singapore's multiracial society.

Tan has engaged law firm Tan Rajah and Cheah led by Senior Counsel Chelva Rajah.

In the Facebook post, Tan wrote:

Both the Government and I have the nation’s best interest at heart. It is in nobody’s interest to have a Reserved Election that is unconstitutional.

This latest development comes more than a year after Tan had announced that he wanted to stand in the coming presidential election in March last year.

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