PORTLAND, Ore. (AP) _ In the 25 years since he won the Heisman Trophy, Terry Baker has spent most of his time reading legal briefs instead of defenses.

The Oregon State quarterback-turned-lawyer sees the legal profession as the field on which many overdue changes in collegiate athletics may come about.

''We're going to have to come to grips with the fact that the colleges are really running a big business,'' the 46-year-old Baker said. ''It could all come to a head in the court system.''

Baker compares the National Football League Players Association free-agency lawsuit against the league with the plight of college athletes, who lose a year's eligibility when they change schools.

''The same principle is involved,'' Baker said. ''Why can't they (college athletes) change if they want to switch majors?''

In 1962, Baker was the first college athlete on the West Coast to be voted the nation's best college football player. He led Oregon State to a 9-2 record and then a 6-0 Liberty Bowl victory over Villanova. He scored the game's only touchdown on a 99-yard run.

With football season over, he started at guard for the Oregon State basketball team, which went 22-9 and advanced to the NCAA Final Four.

He was voted Sportsman of the Year by Sports Illustrated magazine, which called him a ''James Bond in shoulder pads.''

Baker was as successful in the classroom as on the playing field, parlaying his studies in mechanical engineering into a post-graduate scholarship from the National Football Foundation and Hall of Fame.

Baker won the Heisman despite playing in Corvallis, far from the nation's media capitals. He thinks another player from such a town could win the Heisman someday, but it will take an effort similar to that expended for him in 1962. ''A lot of credit has to go to (Coach) Tommy Prothro and Johnny Eggers,'' then Oregon State sports information director, Baker says.

''I think Tommy liked having a star. He liked the big time and having an All-America would bring glamour to the program. You had to run a little bit of a campaign and then you had to have the luck of the draw.''

He says there was a time when he tired of being known as a former Heisman Trophy winner. But now, he adds, ''I'm old enough now that it's flattering for someone to know that I even played.''

Baker's Heisman Trophy sits in a display case at Oregon State. His law office lacks the trappings of a former Heisman winner.

''Call it a personality quirk,'' he said.

He does follow, with considerable agony, an Oregon State football program that shows only 30 victories in the last 15 years.

''I would never have believed the bottom would have fallen out like it has,'' he said. ''Oregon State is just going to have to try harder. If Oregon can do it, there's no reason Oregon State can't.''

Baker was selected by the Los Angeles Rams in the first round of the 1963 player draft, thus beginning three years of limited playing time.

''I wasn't a dropback passer in college,'' Baker said. ''I came into an era when everyone wanted a quarterback who stayed in the pocket.''

He was thrust into the Rams' starting lineup on opening day 1963, one season after winning the Heisman. He was naturally expected to be an instant star.

''I was thrown in too quick, starting the first league game as a rookie,'' Baker said.

When it became apparent that his college skills did not translate well to the professional game, Baker sat on the bench. But he didn't waste his time. He studied law at Southern Cal at night during the season and full time in the off-season.

In 1965, he was involved in a brief, failed experiment to convert him into a running back. In 1966, he played with the Edmonton Eskimos of the Canadian Football League.

By that time, he knew his days in football were numbered. That's why, when offered a contract with the Eskimos in 1967, he turned it down in order to stay in Oregon to study for the bar examination.

''They lost their first exhibition game something like 40-0 and they called me up and offered to set up something where I could play and come down to study,'' Baker said.

No, thanks, Baker said, and football was suddenly in the past.

''Everybody would have liked to continue being a star or an MVP, but there was never any question that my pro football career was going to end someday,'' he said. ''Maybe it would be different if you'd played 10 years.''

He says he is not haunted by his lack of success as a pro. In fact, the lessons of sports have helped him in law and life.

''Whenever someone is under stress, it reveals character. I think sports in general can build character - it's competitive in nature - and competition tends to bring out the best in people.

''It teaches you to accept failure and come back again.''

Can Baker analyze how he accomplished so much in 1962?

''Not really,'' he admitted. ''You just get on that treadmill and you don't have time to think about it.''

The achievements of that year make him think of the late Andy Warhol's definition of fame.

''Those things happen once in a lifetime,'' Baker said. ''That was my 15 minutes.''

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