Former German Chancellor Gerhard Schröder is suing the country's parliament after he was stripped of some state privileges over his close ties to Russia.
Schröder -- who served from 1998 to 2005 -- had lost the right to funding he previously received for his office space and staff.
The 78-year-old is now seeking to restore the benefits, according to his lawyer Michael Nagel.
Schröder's relationship with Russia's energy companies and President Vladimir Putin has come under heightened scrutiny following Russia’s invasion of Ukraine in February.
Nagel said his client had filed a suit with Berlin’s administrative court on Friday, according to the German news agency DPA.
In May, the German Bundestag changed the rules to link some privileges former chancellors receive to their actual duties.
But Nagel says the reasons for the rule change were obvious and wouldn’t withstand legal challenges.
Earlier this week, members of the ruling Social Democratic Party (SDP) rejected a bid to expel Schröder
A committee in Hamburg stated that the former chancellor has caused "damage to the party" but that his actions did not violate their rules.
After intense criticism, Schröder resigned from the board of Russian oil company Rosneft in May and said he had given up on joining the board of gas giant Gazprom.
But the former chancellor has refused to distance himself from Putin and recently met with the Russian leader on a visit to Moscow in late July.
In recent months, some of his staff have abandoned him, but he has retained his police protection and his pension as former chancellor.