Legislation intended to limit the use of union labor on the Dulles Rail project can’t be enforced against the board overseeing that construction, Virginia Attorney General Ken Cuccinelli’s office told state lawmakers this week.

The bill would withhold $150 million in state funding for the project unless the Metropolitan Washington Airports Authority dropped its plans to require contractors on the $6 billion project to use union labor. But Cuccinelli’s office told a supporter of the bill, Sen. Dick Black, R-Loudoun, that the law only applied to state agencies, not regional bodies such as the airports authority.