"If you ask me whether this case is a political process that may have far-reaching consequences, not only in the Netherlands but the whole world, I would say so," Paul Cliteur, a Leiden-based law professor and philosopher told judges.
Cliteur was testifying for the defence as hearings resumed in the case against the far-right politician, accused of insulting a racial group and inciting racial hatred after comments he made about Moroccans living in the Netherlands.
Wilders, 53, has dubbed the case a "political trial."
He has been snubbing the hearings, unfolding at a high-security court near Amsterdam's Schiphol airport, and contends he had simply been exercising his right to free speech.
The Netherlands holds general elections in March and Wilders's far-right Freedom Party (PVV) is riding high in the polls, a close second to the ruling Liberal VVD party.
Due to run until November 25, the trial focuses on a comment made at a 2014 local election rally, when Wilders asked supporters whether they wanted "fewer or more Moroccans" in the country.
When the crowd shouted back "Fewer! Fewer!" a smiling Wilders answered: "We're going to organise that."
"Wilders's viewpoints... are particularly radical in his criticism against Islam," Cliteur told the three-judge bench.
But his remarks at the rally "had nothing to do with racism", Cliteur maintained.
The comments were "rather aimed at halting immigration based on nationality".
"He may just as well have asked 'Do you want fewer Americans or fewer Malaysians', -- the effect is the same."
Wilders's statements were met with outrage, including from the small but vocal Dutch Muslim community. An avalanche of 6,400 complaints followed.
A verdict is expected on December 9. But the hearing took an unexpected turn Thursday when defence lawyer Geert-Jan Knoops interrupted proceedings, demanding judge Eliane van Rens be replaced.
Earlier in the day, she had asked Cliteur several critical questions about his testimony.
"We've come to the conclusion that the judge has not conducted the questioning in an impartial manner," Knoops said.
A legal body composed by the Dutch highest court, the Hoge Raad, will hear the request for a recusal on Friday.
The court also heard from a lawyer representing four aggrieved groups and eight individuals, demanding compensation from Wilders.
"One man said he became depressed, could not sleep and did not feel a valued member of Dutch society any more," Goran Sluiter told the judges.
If found guilty, Wilders could face a two-year jail term or a fine of more than 20,000 euros ($22,100), but experts said a punishment on this scale was unlikely.