A voter-approved Constitutional amendment barring campaign contributions from unions and some state contractors was today ruled unconstitutional by the state Supreme Court.

The decision wraps up a 16-month-long fight over the constitutionality of a law that opponents said curbed free speech rights and which threatened to chill donations to political candidates.

The amendment, which passed with 51 percent of the vote in 2008, bars from political giving holders of large no-bid state contracts, their families and members of boards of directors. It also defined labor unions as no-bid contractors.

Opponents argued the law did not clearly define the types of contracts it applied to or provide state and local candidates with a way to screen donors. The court agreed.