Power conferences are moving closer to banning former NFL players from playing within their membership across 64 schools. 

On Tuesday, the Big Ten became the first conference to levy significant penalties when its athletic directors and faculty athletics representatives unanimously approved a ban on former NFL players pursuing a fifth year of eligibility within their league. Other conferences could soon follow suit, too.

SEC athletic directors are scheduled to meet beginning later Tuesday for a pre-scheduled session over the next two days at the conference's headquarters in Birmingham, Alabama. It's not yet clear whether a similar ban will gain unanimous approval, given that LSU is already flirting with adding two former NFL players to the roster.

The Big 12 is mulling a similar ban, and the ACC is set to meet Wednesday to discuss the subject, sources told CBS Sports. 

The Big Ten's decision and the other conferences' discussions arrive amid growing legal uncertainty and a recent push from players who've signed NFL contracts trying to return to school and even seeking to enter the transfer portal – utilizing recent court rulings allowing players interested in a fifth year of eligibility to return to college football.

The Big Ten made it clear that its ban includes players who signed a professional contract, were on a professional roster, or declared for the NFL draft without withdrawing.

Previously, under the Big Ten's Sportsmanship Policy, standard disciplinary measures gave the Big Ten's commissioner the leeway to levy immediate five-figure fines or hand down suspensions on his own authority, while major escalations -- including extended sideline bans or institutional sanctions -- required only the executive committee's rubber stamp.

Such violations will be dealt with swiftly and decisively. That will surely be the case with other conferences if they implement the same rule, as many in the college athletics space expect. Lawsuits could follow from players -- and potentially schools -- seeking to circumvent these rules, though it appears unlikely to have much impact, at least within the Big Ten, at this point, given the unanimous approval among the 18 schools. 

"The lawsuits are circumventing the NCAA, but now when the league says you can't do it, now you're dealing with problems with your conference," a power conference head coach told CBS Sports.

Several head coaches told CBS Sports they would like to see further punishment, including game forfeitures, if teams play a former professional athlete.

The SEC released a statement Tuesday night urging Congress to pass the Protect College Sports Act in September to better protect itself from such developments, but the league, along with other power conferences, is moving toward individual conference-wide rules and enforcement. 

It also potentially signals the first step toward the long-gestating proposals within the Big Ten and SEC to shoulder enforcement policies under a new rules-and-enforcement model separate from the NCAA. The conferences have been preparing self-governance models in case legislation in Washington, D.C. fails to become law later this year.

LSU has been at the center of the recent controversy after Lane Kiffin secured commitments from two former NFL players -- defensive tackle ZXavian Harris and former Cleveland Browns tight end Dae'Quan Harris. 

LSU athletic director Verge Ausberry has been supportive of Kiffin's plan, though it remains to be seen whether he votes alongside his SEC colleagues this week to ban those players from participating in the SEC.

"There are a lot of parts of this I don't like," Kiffin said Tuesday on The Pat McAfee Show. "I don't think professionals should come back to college sports and college football. But in this instance, these are not players who have gone on to play seasons professionally or randomly filed an injunction. This is part of a specific class that was ruled wrong by the NCAA that was supposed to be [five years to play five seasons]."

The NCAA approved a measure allowing players to play up to five seasons within a five-year span, but only the class of 2023 and later. That decision led to former players from the class of 2022 who had exhausted their four years of eligibility to file lawsuits seeking temporary injunctions for a fifth season. 

Some were successful, leading many players to rejoin rosters across the country -- though LSU is the only school so far to seek out players that landed on NFL rosters.

Nevertheless, there's now growing doubt once again among athletic department, coaching and front-office sources about whether those players will actually be able to play at all this season.