The Parlements were a constant source of trouble under the French monarchy, because they saw themselves as a check on the absolute power of the king, and as a bulwark against the encroachments of the papacy. They often tried to portray themselves as representatives of the National Will, but being rich, conservative lawyers, who had purchased or inherited their offices, they really represented nobody but themselves. Often their causes won popular support because anyone who opposed the king seemed to speak for justice and liberty, but in fact they were just as conservative as the monarchy and their primary complaint was that they didn't have enough say in the government.
The Parlements were responsible for causing the Fronde, blocking taxation reform, and keeping the Unigenitus issue alive for most of the 18th century. They were also partly responsible for the expulsion of the Jesuits.