NEW YORK (CNN/Money) - The National Football League is getting younger, but it isn't ready to open its doors to the youthful college or high school students who dominate the National Basketball Association and Major League Baseball drafts.

The NFL age rules, which prevent drafting players until they are three years removed from high school, have gotten increased attention this week due to a possible legal challenge by Ohio State University star running back Maurice Clarett.

Clarett was suspended Wednesday for at least his sophomore season after being found guilty of accepting thousands of dollars in improper benefits and lying about those payments to investigators. His attorneys say he is considering a challenge to the rules that now stop any team from drafting him until 2005.

The NFL had a record 32 underclassmen picked in this year's draft, with 10 of them going in the first round. That's up from only 12 underclassmen who were picked at all as recently as the 1989 draft, the year before these age rules went into effect.

Even with this year's younger crop of new players, the NFL is a long way from the NBA, where high school student LeBron James was the first pick overall, and college seniors picked in the first round (eight) were outnumbered by freshmen, sophomores and high school students, none of whom would have been eligible for the NFL draft.

Officials with the league and the National Football League Players Association have both said that younger players don't have the size or skills to compete in the NFL.

But there's little doubt that if Clarett was eligible to join an NFL team, some team would take a chance on him. Without the NFL age rules, he might well have gone straight to the NFL without even trying to return to national champ OSU, the way Carmelo Anthony did this year after leading the Syracuse University basketball team to the championship his freshman year.

The NFL says it is confident its rules will withstand any legal challenge.

"We think it's reasonable and in the best interest of the players," said NFL spokesman Greg Aiello. "Without it, you would have more kids leaving school early, dropping out of the educational system to pursue a career in NFL unsuccessfully. They're going to have some agent telling them they are better than they are."

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The NBA once had a rule that prevented players from being drafted until they were out of high school for four years, but that rule was struck down by a federal lawsuit filed by Spencer Haywood in 1971. Sports law experts say that the NFLPA's willingness to accept the NFL age limit might allow the NFL rule to withstand the legal challenge the NBA rule could not.

"I think they're in a stronger legal position but not an absolutely solid legal position," said Fordham University professor Mark Conrad, who teaches sports law. "The question is: Are these players part of the union?"

But even if Clarett had a slam-dunk legal case, he would have to win a relatively quick legal victory to make the 2004 draft, now less than eight months away.

The NFLPA, which represents players already facing some of the shortest careers in sports, has an interest in not bringing in new competition any sooner than necessary. Officials there would not comment on the age rule.

The NFL benefits from the rule as well, said sports marketing expert Marc Ganis. It helps support college football, allowing it to serve as a free minor league system for the NFL. And because college stars have some time to build up a following with fans of their teams before they ever suit up in the NFL, it helps build fan interest in the nation's most popular sport.

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"On a marketing level it's been a real drawback for the NBA to have all these freshmen and high school players in the league," said Ganis.

The NFL's Aiello insists that's not the motivation for the rule, but doesn't deny the marketing benefit. He said the physical difference between football and other major sports makes it necessary for teams to wait to pick players.

"You can't project how they're going to do until they're full grown," said Aiello. "The physical, mental and emotional demands for an NFL player are extraordinary. That's why you see relatively few underclassmen reach the NFL and succeed. Even if you lowered the age limit, that fact wouldn't change."