Hanson questions WA GST share legality

Pauline Hanson says she's keen to investigate whether the federal government is breaching the constitution in the way it distributes the GST.

Section 99 of the constitution states: "The commonwealth shall not, by any law or regulation of trade, commerce, or revenue, give preference to one state or any part thereof over another state or any part thereof".

"This is something I thought about investigating further - maybe the state, for the GST, is being treated unfairly under the constitution," the One Nation leader told reporters in Perth on Monday.

Constitutional expert George Williams said it was true the commonwealth could not discriminate when it came to levying tax, but there were no limitations on granting money to the states.

He said section 96 of the constitution stated: "The (federal) parliament may grant financial assistance to any state on such terms and conditions as the parliament thinks fit."

Section 99 primarily related to commerce and trade not granting money, he said.