The court's posture during a hearing Tuesday contrasted with its decision a year ago to block state lawmakers from putting the advisory measure on the ballot.
The measure, Proposition 49, asks voters whether there should be a federal constitutional amendment to overturn Citizens United, the 2010 ruling that permitted corporations and unions to spend unlimited sums to try to sway voters in federal candidate elections.
The only division on the court Tuesday appeared to be over how broadly a ruling in favor of the Legislature should be written.
Some justices seemed to want a narrow decision based on the right of state legislatures to query voters on possible federal constitutional amendments. Others said California law gives the Legislature the right to put all sorts of advisory measures on the ballot.
Chief Justice Tani Cantil-Sakauye noted that cities and counties regularly put plebiscites on the ballot seeking the views of constituents.
"What is the harm?" she asked.
Justice Carol A. Corrigan suggested there was nothing in the law that prevents the Legislature from taking such actions. "The Legislature has plenary power," she stressed.
The case stems from a conservative group's challenge of Proposition 49, which the Legislature voted to place on the 2014 ballot. The Howard Jarvis Taxpayers Assn. sued, arguing the measure was an attempt to affect voter turnout, and if allowed, would lead to long, cluttered ballots with meaningless propostions.
The state high court, over the objection of the chief justice, decided to remove the measure while the justices considered the challenge. If the Legislature wins the case, the measure will go before California voters in November 2016.
Justice Goodwin Liu expressed concern Tuesday that a broad ruling would give the Legislature unfettered rights that citizens lack. The state high court has ruled in the past that citizens may not put advisory measures on the ballot by initiative.
Liu said the Citizens United measure was "skewed" to attract a vote in favor of repeal and to "marshal" support for the Legislature's viewpoint.
"We need to know where we're headed in this case, because once we open that door, it is very hard to shut," Liu said.
Justice Ming W. Chin asked whether the Legislature could not find a better way to do a poll.
"What about the Internet?" he asked. "What about Twitter?"
But Justice Mariano-Florentino Cuellar noted that state lawmakers clearly have the right to investigate matters of public concern.