Tom Brady; Drew Brees; Vincent Jackson; Ben Leber; Logan Mankins; Peyton Manning; Von Miller; Brian Robison; Osi Umenyiora; Mike Vrabel; Carl Eller; Priest Holmes; Obafemi Ayanbadejo; Ryan Collins; Antawan Walker, individually, and on behalf of all others similarly situated, Appellees, v. National Football League; Arizona Cardinals Football Club, LLC; Atlanta Falcons Football Club, LLC; Baltimore Ravens Limited Partnership; Buffalo Bills, Inc.; Panthers Football, LLC; The Chicago Bears Football Club, Inc.; Cincinnati Bengals, Inc.; Cleveland Browns Football Company LLC; Dallas Cowboys Football Club, Ltd; PDB Sports, Ltd., doing business as The Denver Broncos Football Club, Ltd.; The Detroit Lions, Inc.; Green Bay Packers, Inc.; Houston NFL Holdings, L.P.; Indianapolis Colts, Inc.; Jacksonville Jaguars, Ltd.; Kansas City Chiefs Football Club, Inc.; Miami Dolphins, Ltd.; Minnesota Vikings Football, LLC; New England Patriots L.P.; New Orleans Louisiana Saints, L.L.C.; New York Football Giants, Inc.; New York Jets LLC; The Oakland Raiders, L.P.; Philadelphia Eagles, LLC; Pittsburgh Steelers LLC; The St. Louis Rams LLC; Chargers Football Company, LLC; San Francisco Forty Niners, Limited; Football Northwest LLC; Buccaneers Limited Partnership; Tennessee Football, Inc.; Pro-Football, Inc., Appellants. No. 11-1898 UNITED STATES COURT OF APPEALS FOR THE EIGHTH CIRCUIT June 3, 2011, Submitted July 8, 2011, Filed COUNSEL: For Tom Brady, Drew Brees, Vincent Jackson, Ben Leber, Logan Mankins, Peyton Manning, Von Miller, Brian Robison, Osi Umenyiora, Mike Vrabel, Plaintiff - Appellees: Barbara Podlucky Berens, Justi Rae Miller, BERENS & MILLER, Minneapolis, MN; Christopher R. Clark, Molly Donovan, David G. Feher, David L. Greenspan, Jeffrey L. Kessler, Jennifer Stewart, DEWEY & LEBOEUF, New York, NY; Bruce S. Meyer, James W. Quinn, WEIL & GOTSHAL, New York, NY; Theodore Olson, Andrew Tulumello, Senior Litigation Attorney, GIBSON & DUNN, Washington, DC; DeMaurice F. Smith, NFL PLAYERS ASSOCIATION, Washington, DC; Timothy Robert Thornton, BRIGGS & MORGAN, Minneapolis, MN. For Carl Eller, Priest Holmes, Obafemi Ayanbadejo, Ryan Collins, Antawan Walker, individually, and on behalf of all others similarly situated, Plaintiffs - Appellees: Arthur N. Bailey, Jr., San Francisco, CA; Vincent J. Esades, Samuel D. Heins, David Woodward, HEINS & MILLS, Minneapolis, MN; Mark Feinberg, Michael E. Jacobs, Daniel S. Mason, Shawn D. Stuckey, ZELLE & HOFMANN, Minneapolis, MN; Michael D. Hausfeld, Hilary K. Scherrer, HAUSFELD LAW FIRM, Washington, [*2] DC; Jon T. King, San Francisco, CA; Michael P. Lehmann, San Francisco, CA. For National Football League, Defendant - Appellant: Benjamin Conrad Block, James M. Garland, Gregg Howard Levy, COVINGTON & BURLING, Washington, DC; David Boies, Robert M. Cooper, William A. Isaacson, BOIES & SCHILLER, Armonk, NY; Paul D. Clement, BANCROFT PLLC, Washington, DC; Daniel Joseph Connolly, Aaron Daniel Van Oort, FAEGRE & BENSON, Minneapolis, MN. For Arizona Cardinals Football Club, LLC, Atlanta Falcons Football Club, LLC, Baltimore Ravens Limited Partnership, Buffalo Bills, Inc., Panthers Football, LLC, The Chicago Bears Football Club, Inc., Cincinnati Bengals, Inc., Cleveland Browns Football Company LLC, Dallas Cowboys Football Club, Ltd, PDB Sports, Ltd., doing business as The Denver Broncos Football Club, Ltd., The Detroit Lions, Inc., Green Bay Packers, Inc., Houston NFL Holdings, L.P., Indianapolis Colts, Inc., Jacksonville Jaguars, Ltd., Kansas City Chiefs Football Club, Inc., Miami Dolphins, Ltd., Minnesota Vikings Football, LLC, New England Patriots L.P., New Orleans Louisiana Saints, L.L.C., New York Football Giants, Inc., New York Jets LLC, The Oakland Raiders, L.P., Philadelphia Eagles, [*3] LLC, Pittsburgh Steelers LLC, The St. Louis Rams LLC, Chargers Football Company, LLC, San Francisco Forty Niners, Limited, Football Northwest LLC, Buccaneers Limited Partnership, Tennessee Football, Inc., Pro-Football, Inc., Defendants - Appellants: Benjamin Conrad Block, James M. Garland, Gregg Howard Levy, COVINGTON & BURLING, Washington, DC; David Boies, Robert M. Cooper, William A. Isaacson, BOIES & 1 SCHILLER, Armonk, NY; Daniel Joseph Connolly, Aaron Daniel Van Oort, FAEGRE & BENSON, Minneapolis, MN. For National Hockey League, Amicus on Behalf of Appellant: Shepard Goldfein, James A. Keyte, Elliot Silver, SKADDEN & ARPS, New York, NY. For The Chamber of Commerce of the United States of America, Amicus on Behalf of Appellant: Zachary Fasman, Stephen Blake Kinnaird, Neal Mollen, PAUL & HASTINGS, Washington, DC. For Sports Fans Coalition, Amicus on Behalf of Appellee: Stephen F. Ross, THE PENNSYLVANIA STATE UNIVERSITY, University Park, PA; Daniel Rees Shulman, GRAY & PLANT, Minneapolis, MN. For Major League Baseball Players' Association, National Hockey League Players' Association, National Basketball Players' Association, Amicus on Behalf of Appellee: Donald Aubry, Steven A. Fehr, JOLLEY [*4] & WALSH, Kansas City, MO. For Elected Officials and Small Business Owners, Amicus on Behalf of Appellee: Mark Stancil, ROBBINS & RUSSELL, Washington, DC. For National Football League Coaches Association, Amicus on Behalf of Appellee: Barak D. Richman, Duke University Law School, Durham, NC. COLLOTON, Circuit Judge. This appeal arises from an action filed by nine professional football players and one prospective football player ("the Players") against the National Football League and its thirty-two separately-owned clubs, more commonly known as football teams (collectively, "the NFL" or "the League"). On March 11, 2011, a collective bargaining agreement between the League and a union representing professional football players expired. The League had made known that if a new agreement was not reached before the expiration date, then it would implement a lockout of players, during which the athletes would not be paid or permitted to use club facilities. The League viewed a lockout as a legitimate tactic under the labor laws to bring economic pressure to bear on the players as part of the bargaining process. See Am. Ship Bldg. Co. v. NLRB, 380 U.S. 300, 301-02, 318, 85 S. Ct. 955, 13 L. Ed. 2d 855 (1965). The players, aware of the League's strategy, opted to terminate the union's status as their collective bargaining agent as of 4:00 p.m. on March 11, just before the agreement expired. Later that day, the Players filed an action in the district court alleging that the lockout planned by the League would constitute a group boycott and price-fixing agreement that would violate § 1 of the Sherman Antitrust Act. The complaint explained that "the players in the NFL have determined that it is not in their interest to remain unionized if the existence of such a union would serve to allow the NFL to impose anticompetitive restrictions with impunity." The plaintiffs also alleged other violations of the antitrust laws and state common law. The League proceeded with its planned lockout on March 12, 2011. The Players moved for a preliminary injunction in the district court, urging the court to enjoin the lockout as an unlawful group boycott that was causing irreparable harm to the Players. The district court granted a preliminary injunction, and the League appealed. We conclude that the injunction did not conform to the provisions of the Norris-LaGuardia Act, 29 U.S.C. § 101 et seq., and we therefore vacate the district court's order. A. Some historical background will place this case in context. In Radovich v. NFL, 352 U.S. 445, 451-52, 77 S. Ct. 390, 1 L. Ed. 2d 456 (1957), the Supreme Court held that professional football -- unlike major league baseball -- is not categorically exempt from the antitrust laws. In 1968, the National Labor Relations Board ("NLRB") recognized the NFL Players Association ("NFLPA") as the exclusive bargaining representative of all NFL players, and the NFL and the NFLPA entered into their first collective bargaining agreement ("CBA"). Mackey v. NFL, 543 F.2d 606, 610 2 (8th Cir. 1976). Since then, the relationship between the League and its players has been punctuated by both collective bargaining agreements and antitrust lawsuits. In 1972, several players filed an antitrust action against the League in Mackey v. NFL, alleging that the League's policy with respect to free agents -- that is, players whose contracts with a particular team have expired -- violated § 1 of the Sherman Act, 15 U.S.C. § 1. Mackey, 543 F.2d at 609. This court concluded that the restriction at issue, known as the "Rozelle Rule," unreasonably restrained trade in violation of § 1, because it was "significantly more restrictive than necessary to serve any legitimate purposes" of maintaining competitive balance in the NFL. Id. at 622. While the Mackey litigation was pending, the CBA between the League and the NFLPA expired, and seventy- eight NFL players filed a separate class action antitrust suit against the League. See Reynolds v. NFL, 584 F.2d 280, 282 (8th Cir. 1978); Alexander v. NFL, No. 4-76-123, 1977 U.S. Dist. LEXIS 14685, 1977 WL 1497, at *1 (D. Minn. Aug. 1, 1977). In 1977, the League and the players entered into a settlement agreement incorporating a new CBA that implemented a revised system of free agency known as "right of first refusal/compensation." Alexander, 1977 U.S. Dist. LEXIS 14685, 1977 WL 1497, at *1-2. As part of the settlement, the League withdrew its petition for a writ of certiorari in Mackey. Reynolds, 584 F.2d at 282. This state of affairs lasted until December 1982, when the NFL players engaged in a fifty-seven-day