The Supreme Court let stand yesterday a lower-court decision voiding a lease agreement between a Baileys Crossroads adult bookstore and a company that wanted to break the lease after an employe of the bookstore was convicted of selling obscene films there.

The high court denied without opinion a request to review the 1976 decision by Fairfax County Circuit Court Judge James Keith, who voided a lease between the renter, Crossroads Books Inc., of 5898 Leesburg Pike, and TOA Enterprises Inc.

TOA Enterprises had sued Crossroads Books to break the lease after clerk Allan R. Sands was convicted of two counts of selling obscene films in the store. The lease forbade unlawful activity on the premises.

The bookstore argued that the lease was not violated when Sands was convicted because only the clerk, not the bookstore itself, was convicted. The bookstore should not be held responsible for the actions of others even though they are on the store's premises, the store contended.

The bookstore also argued that a single conviction in the store did not mean that Crossroads used the store regularly for unlawful purposes.

During the hearing on Sept. 22, 1976, Judge Keith said the lease should be rescinded because Crossroads fraudulently represented itself during lease negotiations and engaged in unlawful activity contrary to the lease.

Last July the Virginia Supreme Court denied Crossroads' petition for an appeal.

Also yesterday, the Supreme Court upheld a ruling by the 4th U.S. Circuit Court of Appeals that Virginia's right-to-work law is not applicable to private employes who work on a federal enclave.

The case was brought by employes of a food service company that provides kitchen cleaning services at Fort Monroe, Va. The employes disputed a provision in the collective bargaining agreement between their employer and Public Service Employees Local 572 that required union membership as a condition of employment.

The Supreme Court also refused yesterday to review a decision by the Maryland Court of Appeals that upheld procedures used by Montgomery County in downzoning property in the Friendship Heights area. The downzoning was part of a comprehensive land-use plan that significantly curtails future growth in the area that is already highly developed.

The Supreme Court also let stand the fraud conviction of Louis Pomponio, who along with his two brothers, formerly ran a multimillion dollar building empire in Northern Virginia.