The measure asks voters whether Congress should amend the U.S. Constitution to overturn the controversial 2010 U.S. Supreme Court decision in the Citizens United case, which helped clear limits on independent expenditures in political campaigns.
Brown referred to a message he wrote in 2014 when he took an identical action, even though that advisory measure never made the ballot because of a court challenge.
"To be clear, this bill and the advisory vote it requires has no legal effect whatsoever," Brown wrote in a message.
He noted that the only way to overturn a Supreme Court decision is by Congress convening a convention to amend the Constitution, and he said the Legislature already passed a resolution asking federal officials to take that action.
Brown said he is sympathetic to those who have concerns about the court decision that opened the door to unlimited spending by corporations and unions in political campaigns.
Because much of that spending is done by nonprofit organizations, IRS rules do not require donor identities to be disclosed.
"I, too, believe that Citizens United was wrongly decided and grossly underestimated the corrupting influence of unchecked money on our democratic institutions," Brown wrote. "But we should not make it a habit to clutter our ballots with nonbinding measures as citizens rightfully assume that their votes are meant to have legal effect."
He warned that allowing the advisory measure without his signature is meant to "signal that I am not inclined to repeat this practice of seeking advisory opinions from the voters."
The new bill is authored by Sen. Ben Allen (D-Santa Monica), who noted Wednesday that since the Citizens United ruling was issued, spending by super PACs — funded by organizations without contribution limits — has reached $1 billion.
"People across the political spectrum are fed up with unregulated, unaccountable spending in campaigns," Allen said in a statement. "They deserve to have their voices heard on what has become a destructive force in politics and our system of governance."
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