Here is an article posted by an aggregator specializing in legal articles. It provides information about a recent Michigan law prohibiting state and subordinate entities from favoring unionized contractors in the bidding for construction projects. The article notes,

The Act prohibits any government unit from entering into a construction contract or otherwise funding a construction project involving a contract containing any of the following terms or conditions:

(1) a term that requires, prohibits, encourages or discourages bidders, contractors or subcontractors from entering into or adhering to agreements with a collective bargaining organization relating to the construction project or related projects.

(2) A term that discriminates against bidders, contractors or subcontractors based on their status as a party or nonparty to, or the willingness or refusal to enter into, an agreement with a collective bargaining organization relating to the construction project or related projects.

In addition to the above prohibitions, the Act prevents governmental units from offering incentives such as grants, tax abatements or credits on the condition that the recipient enter into a collective bargaining organization relating to the underlying project or a related project.

Maybe the Federal Government should have such a law for its own bidding. Come 2013?