Ken Cuccinelli (Steve Helber/Associated Press)

The board voted 5-1, rejecting Cuccinelli’s contention that only the General Assembly can designate a special class of citizens.

The Department of Juvenile Justice operates five facilities and a diagnostic facility, and the Board of Juvenile Justice sets broad policy for the agency. More than 800 juveniles are housed in the institutions.

Equality Virginia, a gay rights group, has touted a national study estimating that 8 percent of boys and 23 percent of girls in juvenile detention identify their sexuality as other than heterosexual.

The vote marked another instance where Cuccinelli’s office has become involved in an agency or board policy decision on discrimination.

In at least three other instances since Gov. Robert F. McDonnell and Cuccinelli were sworn into office in 2010, state agencies have had to weigh protections based on sexual orientation against advice from the state’s top elected officials.

Last year, the State Board of Social Services accepted the advice of Cuccinelli and the McDonnell administration and overwhelmingly voted to continue a practice that some argue allows faith-based organizations in Virginia to discriminate in adoptions.

But earlier, the state’s public colleges appeared to reject Cuccinelli’s counsel that they rescind policies that ban discrimination on the basis of sexual orientation.

In 2010, the Board of Corrections reaffirmed a policy prohibiting discrimination on the basis of sexual orientation, overruling concerns expressed by a representative from Cuccinelli’s office.

The juvenile justice board began a massive rewrite of its 300-page regulations in 2009 during the administration of former governor Timothy Kaine. After public input, members say, they decided to include sexual orientation as a protected status.

“The regulations passed by the board today will return to the governor’s office for review as the next step in the process. They will be reviewed then in the coming weeks,” Jeff Caldwell, a spokesman for McDowell, said. “The governor’s office will review the minutes of board’s meeting and the language of the resolutions passed today before making any determination on this issue.”

A spokesman for Cuccinelli did not immediately respond to a request for comment.

The seven-member board is made up of four appointees of Kaine and three appointees of McDonnell.