PORTSMOUTH, R.I. — High school seniors must abide by a new yearbook-portrait policy adopted months after a student went to court for the right to pose wearing armor and carrying a prop sword.

The Portsmouth School Committee's policy prohibits students from posing with objects including props, pets, instruments, hobby items or athletic equipment.

Portraits must depict the student only in a traditional indoor or outdoor background and the new policy requires clothing to be "modest" and to "conform with the school district's dress code." It also contends that the yearbook is "not a public forum."

Patrick Agin, a Portsmouth High senior and a fan of the Middle Ages, dressed in costume for his senior portrait last fall. But the principal rejected the photo, citing a zero-tolerance policy against weapons.

Agin and his mother sued with the help of the state affiliate of the American Civil Liberties Union. The state education commissioner, Peter McWalters, sided with Agin in January, and the district agreed to print the yearbook with Agin's photo.

Principal Robert Littlefield said the new policy was intended to be a formal declaration of what is and is not permitted in official school publications. He said he wanted to avoid situations in which the district was accused of making arbitrary decisions.

"We believe that our students have ample opportunity to express themselves in other areas, and that it's not our responsibility to provide students with a forum to express whatever interest or whatever hobby they may have," Littlefield said in an interview yesterday.

"It's impossible for us to predict what a student may want to have published in our yearbook next year," he added.