In dismissing the charge, Judge Bruce Schroeder said the law on possession was unclear. Rittenhouse was 17 at the time of the shootings.
While a misdemeanor charge, its dismissal carries symbolic significance for a case that has captured the attention of the public in part because it involves a teenager roaming the streets with a semi-automatic rifle who was not immediately brought into custody by the Kenosha police.
The defense had argued that under a strict reading of Wisconsin law a person could carry a rifle at age 16 or 17 as long as it was not considered short-barreled, among other exceptions.
After prosecutors conceded that the barrel of Rittenhouse's AR-15-style rifle was of a length that would not categorize it as short-barreled, the judge dismissed the weapons possession charge, the only misdemeanor count against the teenager.