Nestor wrote on social media that Estonia is a law-governed state and part of that is an independent court that makes decisions not based on a worldview but effective laws.

"In the Soviet Union, the court's decisions were based on the party's decisions — even the judge had to be a member of the party," Nestor said, adding that he sincerely believes that nobody would want such a court to return.

President Kersti Kaljulaid likewise condemned the statement.

"I don't want to talk about the political culture in the parliament nor elementary politeness, as the first is mainly a matter of MPs' internal compass and the other an issue that belongs in the nursery," Kaljulaid wrote on social media on Thursday. "But I can't be silent when the constitutional order and the balance of powers are in danger, even if it is a deliberate provocation. MPs have, or at least should have, the best understanding about what the separation of powers is. Attacking independent judicial authority from the rostrum of the parliament is completely unacceptable."

In a speech made in the Riigikogu on Monday, Helme said in regard to the judges who allowed a same-sex marriage to be entered in the register that he wants their "heads to roll."

"I want a threat to be heard from this rostrum," Helme said. "I want the heads of Virgo Saarmets, Maret Altnurme and Kaire Pikamae to roll because it cannot be that some women come together and just change Estonian laws and then decide that nobody can touch them."

Chief Justice of the Supreme Court Priit Pikamäe has also condemned Helme's statement.

In January, Tallinn Circuit Court ordered the Harju county government to enter into the Estonian population register a marriage concluded between two men in Sweden. In February, Tallinn Administrative Court ordered the Ministry of the Interior to enter the adoption of a same-sex civil partnership into the population register.

The Registered Partnership Act stepped into force on Jan. 1, 2016, but its implementing acts have yet to be adopted in the Riigikogu.

The legislative body finished the first reading of the implementing provisions on Nov. 25, 2015, after which it was decided that discussing the provisions would continue in the Legal Affairs Committee, where the last discussion concerning them took place on Jan. 21, 2016.