Northwestern Wildcats line up in the tight end position against the Syracuse Orange at Ryan Field on September 7, 2013 in Evanston, Illinois.   - 

Football players at Northwestern University are scheduled to vote on Friday whether to join a union.

Student athletes on scholarships are expected to spend 40 hours a week performing and practicing their sport. Some argue that makes them employees, which opens the door to unionization. 

And if players can form a union, "it's possible that the student-athletes' union could negotiate scholarships or other forms of payment," says Gerald Berendt at the John Marshall Law School.

The issue could spread to other private universities and other college sports. But first, the National Labor Relations Board in Washington, D.C. must decide whether student athletes on scholarship qualify as employees.

By Shea Huffman/Marketplace

Follow Jeff Tyler at @JeffMarketplace