The Challenge is being presented to the court by the Canadian group Democracy Watch.

The rules of prorogation as per The House of Commons Procedure and Practice (the green book) stipulate that prorogation may be called to reset a stuck parliament, but may not be called solely to benefit any political party.

Prorogation for as little as one day can reset parliament (all bills before the house are effectively cancelled)

The Canadian Parliament is stuck and a reset is needed, but Trudeau during his resignation speech also mentioned that the Liberals need time to elect a new leader. Parliament was prorogued until 24 March (to give the liberals time to elect a new leader) instead of until the end of winter break, January 27th, when parliament is scheduled to resume.

There is no precedent for this challenge in Canada. However there is a precedent that occurred in the UK during the Brexit debate. The challengers won the court case and prorogation was amended.

Whether or not this challenge to prorogation will succeed is unknown.

This info from Northern Perspective. For those interested I will post the video in the comments section.