A Berlin court is expected to rule on the case of a pro-Palestinian activist who called out the divisive slogan “from the river to the sea” at a rally, in what supporters say is an important test case for Germany.

The trial before a district court of a German woman with Iranian heritage, identified only as Ava M, is one of several since the 7 October Hamas attacks in Israel and the destruction of Gaza that have examined Germany’s limits on free speech.

The defendant, 22, is accused of “condoning the assault by Hamas” by using the slogan “From the river to the sea, Palestine will be free” during a protest on 11 October near the Sonnenallee boulevard in the capital’s diverse Neukölln district.

Condoning a crime can meet with a prison sentence of up to three years or a fine.

A spokesperson for the court, Lisa Jani, confirmed that while there had been about five cases in Berlin involving “rioting” and “incitement” at pro-Palestinian protests, this was probably the first revolving specifically around the use of the politically charged phrase.

Even if the defendant is found guilty on Tuesday, it would be only the beginning of a long legal odyssey of appeals through higher tribunals. “The ruling … would not be binding – we’re the lowest court,” Jani said.

Supporters have announced a rally outside the courthouse in support of the defendant.

Ava M’s legal team said the slogan must be seen as a “central expression of the global Palestine solidarity movement” and that pro-Palestinian activists were resisting attempts to criminalise it.

A lawyer representing her, Alexander Gorski, said German prosecutors’ varying efforts to classify the phrase as condoning criminal acts, inciting hatred or using terrorist symbols illustrated a capricious approach that was having a chilling effect on free political expression.

Gorski said: “What we’ve seen since 7 October is that the right to the freedom of assembly completely depends on the goodwill of the state – and if the state doesn’t want demonstrations to happen, it will just ban (them).”

“Between the river and the sea” is a fragment from a slogan used since the 1960s by an array of activists with different agendas. It has a range of interpretations around the world, from the genocidal to the democratic.

The full saying is a reference to land between the Jordan River to the east and the Mediterranean Sea to the west, encompassing both Israel and the occupied Palestinian territories.

Germany considers support for Israel to be a matter of Staatsräson, or reason of state, at the core of its national identity due to its responsibility for the Holocaust.

The German legal framework assessing the slogan is complex, with courts zigzagging between more and less severe interpretations.

Last November, the interior minister, Nancy Faeser, banned Hamas activities in Germany as well as “from the river”, which she declared to be a Hamas slogan.

In February, the justice minister Marco Buschmann said the phrase could constitute “antisemitic incitement” and be understood as “condoning the killings committed in Israel”.

German police have frequently used the saying as justification to revoke permission for organised protests, or made its avoidance a condition for granting their permission, citing Faeser’s directive.

However, the judicial system has taken a more nuanced view depending on the context of the occurrence and whether it could be interpreted as approval of Hamas’s attacks or a more general call for Palestinian statehood.

Judges in the states of Baden-Württemberg and Bremen this spring rejected activists’ challenges to the Faeser policy, on the grounds the phrase amounted to the use of “symbols of unconstitutional and terrorist organisations”.

But a Bavarian administrative court ruled in June that the phrase to be used in an upcoming demonstration in Munich did not constitute a crime and could not be banned outright, finding that the “benefit of the doubt” around the slogan must prevail.

The Central Council of Jews in Germany, which represents the roughly 200,000-strong community, criticised the decision at the time as “incomprehensible” and said the slogan meant nothing less than negating Israel’s and its Jewish citizens’ right to exist.

“Hamas’ battle cry means the annihilation of Israel and the expulsion and destruction of the Jews living there,” it said, adding it was the German state’s “urgent duty” to “create clarity” about the phrase.