Authorities say Fraser and his pregnant girlfriend were having a dispute late Tuesday night in Haverhill (HAY'-vruhl), when Wallar intervened and subdued Fraser with his department-issued Taser.
Fraser was charged with two assault counts. Wallar was charged with assault and battery with a dangerous weapon. Both pleaded not guilty.
Wallar's lawyer says his client believed his intervention was justified. Fraser's lawyer says the dispute was overblown.