A Fairfax County lawyer who claimed his constitutional rights were violated when he was fined $10 for leaving his car in an official courthouse parking space appealed his case yesterday - and lost.

A s a throng of supportive lawyers looked on, a five-person jury found Vienna attorney Joseph Duvall, a past president of the Fairfax bar, guilty of taking a space reserved for courthouse employes but reduced his fine to $5.

Hanover county Judge Edward P. Simpkins, brought in after Fairfax judges disqualified themselves, immediately suspended the fine and Duvall's three-man defense team said it would appeal the verdict to the Virginia Supreme Court.

Duvall contended that a Virginia constitutional prohibition of "separate emoluments or privileges" for any citizen should extend to the limited parking spaces reserved for county officials at the courthouse.

The public - including lawyers and their clinets - is forced to park in an area described yesterday by one county official as "down a gully and over a hill" from the courthouse.

Duvall took up his crusade after he was ticketed Sept. 15 for parking inan official space. General District Court Judge Robert Hurst found Duvall guilty of violating the traffic ordinance last month fined him $10.

Simpkins said yesterday he sympathized with Duvall, but added that there would be "chaos" without a system of allocated spaces.