WASHINGTON (AP) — A federal judge in Washington ruled Tuesday that a group of Democrats in Congress can proceed with a lawsuit against President Donald Trump alleging his businesses violate a constitutional ban against gifts from foreign governments.

But the case could soon be bottled up if Trump’s lawyers succeed in appealing the judge’s ruling.

In a 48-page opinion, District Court Judge Emmet G. Sullivan ruled that Democrats’ claims that Trump has violated the emoluments clause of the constitution provide a valid “cause of action” against the president.

Sullivan cited a Maryland federal judge’s ruling in a similar emoluments case against Trump that concluded the scope of the constitutional ban on foreign gifts was broad — based on “overwhelming evidence.”

But even as Sullivan allowed the D.C. case to go forward, it faces the same legal constraints that have bogged down the Maryland case. In that case, a federal judge gave a green light to efforts by attorneys general in Maryland and the District to gather evidence to prove emoluments violations. But Trump’s lawyers blocked the move by persuading a federal appeals court in Richmond to review the case.