Poland drifting further into EU legal limbo

"The seconded judges are ... not subject to the ordinary rules, but to a rather special - and very troubling - legal regime," in which the Polish minister can promote or fire them on his whim "at any moment," Bobek noted.

The Polish regime did not give "reasonable confidence that judges ... are not subject to external pressure and political influence, and have no vested interest in the outcome of the case," the ECJ expert added.

"In circumstances such as those ... the minimum guarantees necessary to ensure the indispensable separation of powers between the executive and the judiciary are no longer present," Bobek said.

The ECJ is not bound to follow the advocate general's opinion, but does so in most of its rulings.

The verdict usually comes a few months after the opinion comes out.

Meanwhile, the fact Poland's ruling nationalist and populist Law and Justice Party (PiS) has already used judicial reforms to go after judges it did not like for political reasons showed how real the problem was.

One of them, Igor Tuleya, is facing up to three years in prison on a disciplinary technicality after incurring PiS' wrath.

The fact the Polish justice minister, Zbigniew Ziobro, is on the far right of even the PiS government makes matters worse.

Some EU countries, such as Ireland and the Netherlands, have already halted extraditions to Poland on grounds that rule of law had broken down there.

And the European Commission has launched a string of ECJ challenges, as well as sanctions proceedings, to try to stop the PiS juggernaut.

The ECJ complaint against Ziobro's new powers was brought to Luxembourg by a district court in Warsaw.

But Polish reforms are also trying to gag judges from referring thorny questions to the EU tribunal in future.

And PiS-loyal judges on Poland's constitutional tribunal are currently deliberating whether Polish law or EU law has primacy in the country, in a ruling which could spell a legal crisis for Poland's EU membership.