The United States Supreme Court has made a significant ruling, allowing President Donald Trump to begin implementing measures from an executive order aimed at restricting mail-in voting in many states and Washington, D.C.

However, this ruling does not necessarily mean that the plan to restrict mail-in voting will be implemented smoothly. Legal challenges to the executive order could still cause issues for the plan before the midterm elections in November.

The ruling on Monday means that the Department of Homeland Security can begin moving forward with compiling state-specific lists of people it believes are eligible to vote in the states, all led by Democrats, that had challenged the executive order.

Another part of the executive order required the U.S. Postal Service to require states that want to send ballots through the mail to submit lists of eligible voters with information allowing those ballots to be tracked by the government. A lower court had blocked this policy nationwide in a separate case, meaning that more legal action will be needed before the postal service can continue.

The high court’s ruling did not address the overall legality of the executive order. Instead, it focused on the specific issue of whether the Department of Homeland Security can begin compiling the lists of eligible voters.