Lobbying compliance lawyers around Washington are drawing attention to a provision in the defense authorization law Congress passed in December.

It bars retiring military officers of high rank and top Defense Department civilians who leave the Pentagon from lobbying there for two years, while some lower level officers now face a one-year lobbying ban.

In a briefing for clients last month, the law firm Covington warned that the new rules “could have a substantial impact on defense contractors and others who recruit DoD personnel.”The law left many of the details to be written by the Pentagon’s Standards of Conduct Office, such as which civil servants it will cover.

But it’s clearly wide-ranging in the limitations it requires of ex-DoD employees, barring not only direct contacts with Pentagon officials but also any work done to prepare for a lobbying meeting, or advice to lobbyists to help them in such a meeting. It also bars the former employees from engaging other executive branch agencies on matters that concern the Defense Department.