The Senate Judiciary Committee asked Major League Baseball and commissioner Rob Manfred to explain the potential impact of stripping away the league's antitrust exemption on the minor leagues.
Democratic Sen. Dick Durbin of Illinois and Republican Sen. Chuck Grassley of Iowa sent the letter on Monday and asked for a response from Manfred by July 26. The letter was also signed by Democrat Sen. Richard Blumenthal of Connecticut and Republican Sen. Mike Lee of Utah.
"Your answers will help inform the Senate Judiciary Committee's analysis of this century-old exemption," the letter reads.
The committee previously sent a letter in late June to non-profit group Advocates for Minor Leaguers, which recommended that Congress create legislation that nullifies the exemption for minor leaguers.
"We look forward to providing detailed information to the committee regarding baseball's limited antitrust exemption and how it has provided franchise location stability at the major league level, maximized the availability of minor league baseball for fans and quality employment opportunities for aspiring major leaguers," the league said in a statement.
In a statement, Advocates for Minor Leaguers said that the exemption has "dire consequences for minor league baseball players and fans."
The letter is the latest movement in regard to life in the minor leagues. On Friday, MLB agreed to pay minor leaguers $185 million to settle lawsuits about alleged violations of minimum wage laws.
In 1922, the Supreme Court ruled that MLB was exempted from the Sherman Antitrust Law of 1890, allowing the league to have an effective monopoly on baseball in the United States.
Outlawing MLB's antitrust exemption would fundamentally change the business of baseball in America.
The uniform player contract signed by every minor leaguer states that teams control the rights of players for up to seven years in the minor leagues and seven years in the major leagues. Due to the antitrust exemption, if a minor leaguer decides to stop playing the sport before the seven years elapse in the minors or the majors, the team owns the rights to the player and he cannot play the sport professionally elsewhere unless he is released from his contract.