An anti-union Idaho law approved by the legislature just four years ago has been nullified even before it took effect.
The Fairness in Contracting Act sought to forbid unions from using funds collected from members to fund contractor bids.
Construction unions call the strategy "job targeting" or "market-recovery" programs.
Union contractors bidding on jobs can use funds from union dues to lower their labor costs and thus compete with non-union builders. For example, a contractor paying $20 an hour could collect $5 an hour from union members and compete with other bidders on a job which pay $15 an hour.
But Idaho banned the practice in 2011.
Before the law could even take effect, a federal judge issued an injunction, and now appeals judges of the 9th Circuit Court have upheld the ban.
They ruled that federal law - including the National Labor Relations Act - is superior to state law. Additionally, as one judge wrote, what workers do with their money through a union is of no concern to federal law.
The appeals judges held that Idaho's criminal penalties for violating the act would go far beyond penalties provided by federal law.
It's been a tough year in federal court for Idaho. Among other reverses, the state's Ag-Gag law was struck down and its same-sex marriage constitutional ban was wiped out.