Germany on Friday enshrined reforms designed to guarantee the independence of the country’s Constitutional Court, with lawmakers eyeing the threat posed by populist parties ahead of elections expected in February.

The package was approved by the Bundesrat, Germany’s upper house, one day after passing the lower house with broad cross-party support.

The new law enshrines key aspects of how the Constitutional Court functions in Germany’s constitution, known as the Basic Law.

It formally fixes the court’s size at 16 judges and sets out 12-year terms for judges, term limits and the mandatory retirement age of 68 years.

Supporters have described the move as a way to insulate the top court from possible political interference in the future, since changes to the Basic Law require two-thirds majorities in parliament.

Bremen Premier Andreas Bovenschulte on Friday said the package defends the independence of the Constitutional Court from outside influences, pointing to judicial crises in other European countries such as Poland and Hungary.

“Here in Germany, we are making our highest court watertight,” he said.

Rules for the Constitutional Court were previously laid out in German law, which can be amended with a simple majority in both chambers of parliament.

The changes also create a new mechanism for confirming judges to the court through parliament, aimed at making it harder for a minority party holding more than a third of seats to effectively veto nominees.

Of the country’s 16 federal states, 15 supported the package in the Bundesrat on Friday, with only the eastern state of Brandenburg abstaining.