An Alexandria judge yesterday dismissed charges that developer Charles M. Fairchild illegally chopped down hundreds of trees last fall, saying the city had failed to put "the smoking chainsaw in Mr. Fairchild's hand."

Fairchild's son, with the same name, and two other men were seen by city police cutting the trees on land beside the George Washington Memorial Parkway last Nov. 16. That activity apparently violated a law enacted in October by the City Council requiring a permit for cutting down trees more than four inches in diameter in certain locations.

Alexandria General District Judge Robert T.S. Colby ruled yesterday the city had failed to prove that the father, who was charged with the offense, ordered the tree cutting or was responsible for it.

Alexandria City Council member Ellen Pickering, who introduced the tree ordinance, told the court she called Fairchild on Nov. 15 and asked him "What in Sam Hill are you doing? ... and he said 'That's my property and I can do with it what I wish.'"

Fairchild also told a Washington Post reporter about the same time that he had the trees cut down "because every year they get bigger and bigger and cost more to remove"... and that someone had offered to cut the trees for firewood. The "somebody" later turned out to be his son.

But Judge Colby chided Assistant City Attorney Nolan Dawkins: Fairchild "has got you outfoxed. That's what it amounts to, Mr. Dawkins. He didn't tell him (his son) to do it. You've got to prove it... You've got to put the smoking chainsaw in his (Fairchild's) hand."

The judge also criticized the city tree ordinance as poorly "drawn" by the City Council and implied it was probably unconstitutional.

The tree cutting outraged Pickering and other City Council members as well as officials of the National Park Service, who called it "upsetting and irresponsible." Secretary of Interior Cecil B. Andrus later promised to provide legal assistance to the city in prosecuting Fairchild, although no Interior Department lawyers were present at yesterday's trial at City Hall.

The 300 to 400 trees, many above 40 and 50 feet tall, screened the scenic parkway from the huge Potomac railroad yards just south of National Airport. Fairchild has a long-term lease on about 40 acres of railroad land there where he proposes to build a $300 million high-rise complex that he calls Potomac Center.

The major entrance to the Potomac center would be the George Washington Parkway, under a complicated land swap made in 1970 between Fairchild and the park service, in which he was given access to the parkway in exchange for 28 acres of marshes he owned at Dyke Marsh along the parkway south of Alexandria. He had proposed dredging the marshes there and creating a "Palm Beach-type" waterfront community.