In the words of one legal expert, the National Football League has now entered "Bizarro World."

It is there because federal judge Susan Nelson on Monday issued an injunction against the NFL lockout – essentially saying that the owners cannot prevent their players from reporting to work and, it seems, playing football. The full ramifications of Judge Nelson's ruling are not yet plain. Further legal actions in her court and beyond in the coming days and weeks could add a measure of clarity to the question of what this all means for pro football in 2011.

But what is clear is that the NFL now faces an unprecedented level of uncertainty.

On Tuesday, players returned to their training facilities only to find empty hallways and orders to not work the weights – a situation NFL Players Association Executive Director DeMaurice Smith called "chaos." In an opinion article for The Wall Street Journal, Commissioner Roger Goodell countered that the ruling could "alter professional football as we know it."

Allowing football players to play without a union (which was disbanded when talks broke down) or a collective-bargaining agreement (which expired last month) would lead to league anarchy, he wrote: All players would become "independent contractors" with the power to dismantle league-wide arrangements like free agency, salary caps, and even the draft.

His pronouncement is partly hyperbole, legal experts say, but it aptly describes how thoroughly Nelson has upset the NFL's apple cart. For as long as Nelson's ruling remains in effect, everything from free agency to the salary cap are in play, with the NFL having lost much of its leverage to bring the players into line.

The league's immediate recourse is to try to get Nelson to issue a stay on her own injunction until legal appeals play out. Nelson said she could do this later this week. If she does not, the NFL will hope that that the Eighth Circuit Court of Appeals in St. Louis overturns or stays Nelson's ruling. The league has already appealed to the Eighth Circuit.

But even if the league is successful in the Eighth Circuit, that process could take time, and if no stay is issued, the NFL would remain in limbo, forced to abide by a ruling it was contesting. Research shows that appellate courts usually reverse sports-related antitrust rulings from lower courts, says Michael LeRoy, a sports- law professor at the University of Illinois in Champaign. But he adds: "Everybody who touches this believes it's uncharted territory."

A lawless league

The object of the legal wranglings is the NFL's $9 billion war chest. Owners felt the previous collective-bargaining agreement favored the players too heavily. They wanted a larger chunk of that revenue, and when they could not agree to a new pact with players, they locked the players out at midnight on March 11.

Mr. Goodell's lament in The Wall Street Journal argues that the last thing the league needs is to throw out the principles that have made it so successful – something he argues could happen under Nelson's ruling.

"What Goodell is trying to say is, undeniably, the system has worked for a long time in escalating player salaries, elevating franchise values, and making everybody associated with the NFL far better off than with a different system," says David Carter, director of the Sports Business Institute at the University of Southern California in Los Angeles.

Few experts believe the players want the current, contract-less situation to become the law of the NFL, though. "Both of the parties know that ultimately it's not going to end up this way," says Michael Cramer, the former president of pro hockey's Dallas Stars and now a professor at the University of Texas in Austin. "We're not going to have a wide open league where each player is negotiating for himself. It can't work, and the union gets it."

Pittsburgh Steelers player representative Ryan Clark said as much on ESPN Tuesday. "We did love the arrangement that we had, and this year the NFL owners opted out of that arrangement," Mr. Clark said. "The guys don't want to become independent contractors without a draft. Many of the things [said by Goodell] in that piece were false."

What the players do like about Nelson's ruling is that it has, at least temporarily, shifted the balance of power in negotiations. So long as the lockout held, the owners were seen as being in the position of power. Now, Nelson's ruling threatens to reverse that.

"That's what's going on [in the courts] – a way of redefining the relationship," says Professor LeRoy of the University of Illinois.

More problems loom for owners

Even bigger problems for the owners could come next month. A cornerstone of their lockout plan is the league's current TV deal, which guarantees $4 billion to the league even if no football is played this season. Another federal judge, David Doty, will hold a May 12 hearing to decide whether that deal violated the previous collective-bargaining agreement and whether the owners therefore need to pay players damages.

If Judge Doty rules for the players in the case, then major leverage would shift to the players and "it's all over for the NFL" and its lockout, says LeRoy. "It's the fourth quarter and the game is on the line here."

It is, to say the least, a confusing situation.

"We're in this interesting position where you have management wishing for a union, and the union wishing for no union – and that doesn't happen in any other industry other than sports," says Mr. Cramer. "Unfortunately the law wasn't built for the NFL, so that's created some interesting hoops to jump through on the way back from Bizarro World."