The Supreme Court has rejected a request to hear a case that enables states to require proof of citizenship for those applying to vote in federal elections. This judgment effectively upholds a lower court ruling against the states of Kansas and Arizona in the United States.

These states wanted the U.S. Election Assistance Commission to change its registration requirements to include proof of citizenship for those applying to vote in federal elections, as the states require these for using in their state forms.

By not taking the case, the Supreme Court leaves in place a November 2014 ruling from the 10th U.S. Circuit Court of Appeals that the states cannot require the documentation for applicants using the so-called “federal form.”

Voting rights advocates hailed the court’s decision to not take up the case. Currently, the federal agency’s form only requires applicants swear eligibility under penalty of perjury.

Several law firms that represented the group praised the Supreme Court, for securing a critical victory to strengthen the right to vote in federal elections in Arizona and Kansas and reaffirming the important role Congress plays in preserving a fair voter registration process across the country.

“This is a very big deal,” said a law professor, in reaction to the ruling.