A long-running legal battle about whether a drawing of a steaming pile of excrement was damaging to the French far-right leader Marine Le Pen is finally due to be resolved.

Judges at France’s highest court will sit down on Friday afternoon to begin deciding on their final ruling in a seven-year legal case after Le Pen sued a TV presenter for defamation when he held up a drawing depicting her as excrement during a Saturday night talkshow.

The mock election poster, reading: ‘Le Pen, the candidate who is like you.’ Photograph: Twitter

Le Pen, the leader of National Rally, formerly Front National, first sued in 2012 in the run-up to a presidential election campaign.

In the TV show, the presenter Laurent Ruquier held up a drawing from the satirical weekly Charlie Hebdo of a mock election poster depicting a pile of excrement in front of the red, white and blue backdrop of the French flag and the words: “Le Pen, the candidate who is like you.”

In what became known as “the case of the steaming excrement”, Le Pen’s lawyers argued that the act of showing the picture went beyond free speech and was an insult to her dignity. The TV presenter’s defence said it was a humorous show, drawings of mock election posters for other candidates had been held up and there was no intention to damage Le Pen.

A first court hearing and an appeal hearing dismissed Le Pen’s case, but a third trial was ordered. At appeal level, although the drawing of excrement was found to be offensive, judges decided that showing it on a TV show was not punishable by the law.

Friday’s final supreme court deliberation is the fifth time the case has been heard.

National Rally, which came first in the European elections in France this year, is in campaign mode for local elections next spring, seeking to hold on to its 11 mayors and gain more in its heartlands in the north and south-east.