The money is being spent to defeat Gov. Jerry Brown's tax measure, Proposition 30, and win approval for Proposition 32, which bans payroll deductions for political giving.
The Fair Political Practices Commission won the first round in court, arguing it's imperative the non-profit unmask the donors financing the political ads.
"If the information is not disclosed immediately, each day brings more public harm and less public knowledge of this contribution before the election," said Gary Winuk with the Fair Political Practices Commission.
But Bradley Benbrook, the attorney representing ARL, says the constitution allows people to express their political opinion through donations.
"The First Amendment rights can only be interfered with if the rules are very clear that the FPPC has this authority, and they do not," said Benbrook.
The judge ruled the ARL must hand in by Monday afternoon reasons why it shouldn't have to disclose. And there's no early hint on what those documents will say.
"We're going to let our papers speak for themselves," said Bradley.
With the election less than two weeks away, government reform groups and the governor warn Californians to be suspicious of ARL's opposition to Prop 30 and support of Prop 32.
"It appears to be money laundering. [The money] is coming from unknown donors through a non-profit, out of state, and then suddenly landing in California, and they're failing to disclose," said Phillip Ung with the group California Common Cause.
"We're talking about a very small group of very powerful and very wealthy people. My hunch is some of that money has been-re routed from Arizona through this phony committee into California," said Brown.
Both sides return to court on Tuesday. Without Thursday's hearing to set that date, it could have taken months to resolve the issue -- not in time for the election.