A more thorough explanation:

À LA GRANDE GREVAUNCE

a la grande grevaunce (ah lə grənd gruh-vuhns). [Law French] To the great grievance.

The term à la grande grevaunce is a legal term that means "to the great grievance." It is often used in legal documents to indicate that a particular action or decision has caused significant harm or injury to someone.

• The court's decision to deny the plaintiff's claim was a la grande grevaunce, as it caused significant financial harm to the plaintiff.
• The new law has been a la grande grevaunce to many small business owners, who are struggling to comply with its requirements.

In the first example, the use of the term a la grande grevaunce indicates that the court's decision had a significant negative impact on the plaintiff. In the second example, the term is used to describe the harm caused by a new law to small business owners.