BRUSSELS, Aug. 14 (Xinhua) -- In the latest sign of acrimony between Poland and the European Union (EU) over Poland's judicial reform, the European Commission decided Tuesday to follow up with a legal step against Warsaw.

The Commission announced in a press release that it had decided to send a "reasoned opinion" to Poland regarding the reformed law on its Supreme Court.

It's a follow-up to the Commission's "letter of notice" on July 2 when the Commission launched a so-called infringement procedure against the country.

Explaining the move, the Commission underlined that "the response of the Polish authorities does not alleviate the Commission's legal concerns."

The Commission insisted "the Polish law on the Supreme Court is incompatible with EU law as it undermines the principle of judicial independence."

Poland has been given one month to "take the necessary measures" to comply with the reasoned opinion.

If it fails to do so, the Commission may refer the case to the Court of Justice of the EU.

The contentious law allows the Polish president to prolong the mandate of current judges for three years and renew it once. It also lowers the retirement age of Supreme Court judges from 70 to 65.

A dialogue on rule of law between the bloc and the Eastern European country has been underway since last December when the Commission triggered Article 7 of the EU treaty against Poland over the dispute.

Dubbed the "nuclear option", Article 7 has never been triggered against any EU member state before. The procedure could eventually lead to Poland losing its voting rights in the 28-member bloc.

Nevertheless, the Commission reiterated that the ongoing rule of law dialogue with Poland remains the Commission's preferred channel for "resolving the systemic threat to the rule of law in Poland."