Le Pen took the stand on Monday, in her first of three expected days of testimony. The widely awaited trial, which comes almost a decade after initial investigations started, threatens to undermine her party's efforts to polish its image ahead of a 2027 presidential vote many believe she can win.
Le Pen, the RN itself, and 24 others - party officials, employees, former MPs and parliamentary assistants - are all accused of using European Parliament money to pay staff in France who were working for their party, which at the time was called the National Front.
French far-right leader Marine Le Pen is facing court on charges of embezzling EU funds. (AP PHOTO)
Le Pen and her co-defendants deny the charges, saying the money was used legitimately, and arguing the allegations show too narrow a definition of what a parliamentary assistant does.
On Monday, Le Pen outlined the basis of her defence, telling the court that she believed a Member of the European Parliament's role was as much to push their party's agenda in France as it was to work on legislation in Brussels.
"I don't see the difference between a national MP's task and a European MP's task, except the scale," Le Pen said.Â
"We're doing politics!"
If found guilty, defendants could face a potential jail sentence of up to 10 years and a 1 million euro ($A1.6 million) fine. Those like Le Pen who were elected officials at the time risk being barred from public office for up to 10 years, while the unelected could face a five-year ban.
If Le Pen was cleared, it would add credibility to her and political party, as they seek to leave behind a reputation for racism and anti-Semitism when her father, Jean-Marie Le Pen, 96, ran the National Front.
EU lawmakers are allocated funds to cover expenses, including their assistants, but are not meant to use them to cross-fund party activities. The European Parliament has estimated the damage of the alleged crimes at 3.5 million euros ($A5.7 million).
The trial will last until November 27.