There have been violent clashes in northern Germany after around 7,000 demonstrators turned out to oppose a rally by a far-right party.
Most of those arrested were left-wing activists
Police used water-cannon against the protesters in the city of Kiel to keep them away from a few hundred supporters of the National Democratic Party (NPD).
More than 40 people were arrested as protesters threw stones and bottles and set rubbish containers alight.
The German government has likened the NPD to an embryonic Nazi party.
It has tried and failed to have it banned.
But the head of Germany's highest court said in an article in the Sunday newspaper Bild am Sonntag that a ban was possible in the future.
"The suspension of proceedings to ban [the party] then does not represent a pre-ordained decision on future efforts to ban [it]," Constitutional Court President Hans-Juergen Papier wrote.
The clashes broke out after a small group of violent protesters tried to break away from the mainly peaceful left-wing protest to attack a barricade of 2,000 police separating the two demonstrations.
They lobbed stones, bottles and firecrackers, in what Kiel police spokesman Hans-Joachim Schmidt called "massive and difficult" clashes.
Forty-two people were arrested, 38 of them leftists.
Last week NPD members caused outrage by storming out of the regional parliament in the state of Saxony, during ceremonies to commemorate those killed at the Nazi death camp at Auschwitz.
The party had its best showing in elections for six years in September, capturing nearly 10% of the vote in the state's elections.
Elections in the region of Schleswig-Holstein, of which Kiel is the capital, are to be held on 20 February. No far-right parties are currently represented in its legislature.