Justice Department lawyers say a federal trial judge in Washington has crossed a line, undermining separation of powers — and potentially risking national security — to resolve a civil lawsuit that pits a former federal drug agent against an ex-CIA officer and an ex-State Department official.

In August, Chief Judge Royce Lamberth of the U.S. District Court for the District of Columbia ordered the government to provide security clearance for six private lawyers on both sides of the case. Lamberth said the lawyers need confidential information in order to litigate allegations that Richard Horn, then with the Drug Enforcement Administration (DEA), was secretly recorded by CIA and State Department employees. The twist is that the classified information at issue resides in the memories of the plaintiff and the defendants themselves. (Lamberth’s order does not compel the government to turn over documents.)