Gallagher case another precedent: expert

Constitutional law expert George Williams says Labor is right to say the High Court decision in the case of former senator Katy Gallagher sets a precedent.

However, he says the coalition also has a point in saying the court reached its conclusion - that Ms Gallagher is disqualified - by "developing and applying its prior decisions" such as the Sykes and Canavan cases.

"Labor is correct in that every High Court decision sets a precedent of some kind," Professor Williams told AAP on Thursday.

"That's the nature of the court deciding on each particular case.

"Here they have done so by establishing how the law operates in the context of someone in Katy Gallagher's position. The court had not previously decided how the law applies in this fact situation."