Campaigns for next year’s U.S. presidential election are in full swing. That means staffers are being hired. And with employees, of course, come potential legal issues. Several Democratic candidates’ campaigns have already encountered at least one such issue: union organizing.

On August 6, it was announced that employees working on Sen. Cory Booker’s campaign decided to select Teamsters Local 238 as their bargaining representative. Booker’s campaign was receptive to the unionization effort, as his campaign manager stated: "Cory Booker has a longstanding relationship with the Teamsters and organized labor and we share common goals, like rewarding hard work with a living wage and good benefits. We are proud to become a unionized campaign and celebrate this step forward together."

While this election cycle marks the first time any U.S. presidential candidate’s campaign has decided to unionize, Booker’s campaign actually is not the first to do so. Prior to this, the staffers working on the campaigns of Sens. Elizabeth Warren and Bernie Sanders formed their own unions. Notably, the Teamsters weren’t the chosen labor organization in those cases. The International Brotherhood of Electrical Workers represents Warren’s workers, and the United Food and Commercial Workers represents staffers for Sanders.

Stay tuned to see if more campaigns follow suit and whether the labor agreements reached in each of these instances have any impact on how the campaigns are run.