The law requires applicants who apply for a license to carry a concealed firearm demonstrate a "good reason to fear injury to his or her person or property."
In a one-page order, the three-judge panel of the United States Court of Appeals for the D.C. Circuit agreed to expedite the case with final briefs due in early August.
Many believe that the issue of concealed carry firearms might be the next Second Amendment issue to reach the Supreme Court, although in recent years, the justices have seemed reluctant to wade into the issue.
In a statement, D.C. Attorney General Karl A. Racine said he was pleased with the order.
"This is good news for public safety in our city, because it means we may continue enforcing our gun laws in full," he said in a statement.
"The District's gun laws are constitutional, reasonable and in line with laws in other states that three other federal appellate courts have upheld," he said.
On May 17, U.S. District Court Judge Richard J. Leon granted a preliminary injunction in the case.
"I find that the District's 'good reason' requirement likely places an unconstitutional burden" on the right to bear arms, he wrote. In the opinion, he relied upon District of Columbia v. Heller, a landmark 2008 decision by the Supreme Court.
"In Heller, the Supreme Court unequivocally asserted that the 'enshrinement of constitutional rights necessarily takes certain policy choices off the table,'" Leon wrote.
'The District's understandable, but overly zealous, desire to restrict the right to carry in public a firearm for self-defense to the smallest number of law-abiding, responsible citizens is exactly the type of policy choice the justices had in mind."
The challenge is brought by the Pink Pistols, a shooting group.