A Towson District Court judge yesterday dismissed criminal battery and trespassing charges filed last month against the executive director of the Teachers Association of Baltimore County in a dispute with a rival union.

Judge Michael L. McCampbell found that if physical contact did occur between Thomas E. Harvey of the teachers association and Susan Orthaus, president of the Public School Nurses Association, it was incidental and without criminal intent.

He also ruled that Mr. Harvey was not guilty of trespassing at a nurses association meeting he attended without invitation Feb. 15 because he left when he was told to go.

Mrs. Orthaus, who filed the charges, testified that Mr. Harvey was angry at being asked to leave and pinned her against a wall in the hallway outside the meeting room. Mr. Harvey said he had not touched Mrs. Orthaus, though he said he was anxious to persuade her of his views in the labor dispute. Mrs. Orthaus and Mr. Harvey testified yesterday that he told her in the hallway to "stop lying" to her members about the nature of an informal labor agreement her association had with the school board. She then walked away from him and went to summon police.

Two teachers association witnesses backed up Mr. Harvey's contention that there was no physical contact between him and Mrs. Orthaus, while Mrs. Orthaus was the only witness for the prosecution. Judge McCampbell said both accounts were credible.

Nurses association attorneys said they were preparing a civil suit.

The groups are competing to represent 137 elementary school nurses whose jobs were transferred last year from the county health department to the school board.

Mrs. Orthaus' association represents those nurses, who make up a large part of its membership. But because of the job transfers, it lacks the legal authority to negotiate a binding contract with the school board. The teachers association represents secondary school nurses and also wants to represent elementary school nurses.