Over the past few weeks, President Donald Trump’s Executive Order (EO) on visas and refugees has dominated the news. Executive orders, which are legally binding directives made by the President in order to direct federal agencies, are often controversial, however Trump’s immigration EO seems to have procured more negative attention than any EO in recent history.

According to USA Today, in addition to suspending all refugee resettlement into the U.S. for four months (and refugee settlement from Syria indefinitely), Trump suspended U.S. entry by citizens of seven majority-Muslim nations (Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen) on non-immigrant visas, including people holding dual citizenship with other nations. One of the many problems with the ban itself (in addition to its questionable legality) is that for a number of individuals and entities, the EO is simply unclear.

The NBA recently reached out to the U.S. State Department for clarification on how to interpret the EO in protecting their players during international travel. Given that 29% of NBA players are foreign born with green cards or employment-based immigration visas, the NBA has a serious interest in figuring out exactly what the immigration ban means. For athletes like Thon Maker (Milwaukee Bucks power forward from Sudan) and Luol Deng (Los Angeles Lakers small forward from Sudan), traveling to Canada in order to play against the Toronto Raptors could result in significant problems as they attempt to re-enter the U.S. Sports Illustrated reports that, “Deng and potentially Maker’s capacities to re-enter the U.S. [though they maintain dual citizenship with Great Britain and Australia, respectively] would, like other persons in their position, be contingent upon the results of an uncertain ‘case-by-case’ evaluation as directed by the Department of Homeland Security.”

Of course, the above issues will be largely affected by the legal battle that is currently taking place in courts across the U.S. over the legality and enforceability of Trump’s Immigration EO. Nevertheless, for now, the NBA and other professional leagues ought to take every precaution to make sure that players from “countries of concern” are scheduled to leave the country on business won’t get stranded overseas or face issues upon attempted re-entry into the U.S.

Nick Aquart is a Sports Highlight Contributor for the Harvard Journal of Sports and Entertainment Law and a current first year student at Harvard Law School (Class of 2019).