Nearly half of the lobbyists who were registered with Congress in 2011 and then went “inactive” in 2012 remained with the same employer, and many continued to influence public policy, according to a study released Wednesday.

The finding by the nonpartisan Center for Responsive Politics illustrates a factor behind the recent decline in federally reported lobbying fees and the number of active lobbyists on K Street: Professionals are taking on roles that leave no public trail because their activities fall outside the scope of disclosure laws.

“Much of the decline in lobbying activity is not a decline at all, but rather the side effect of lobbyists and lobbying firms taking advantage of a feature of the law which allows them to continue influencing policy from ‘behind the scenes,’” the study concludes.

“By working as policy advisors and in other ‘non-lobbyist’ positions, former lobbyists can keep their current jobs but escape the consequences of being a registered lobbyist, leading people in and out of lobbying to suggest that those consequences act as a deterrent to transparency,” the study states.

The Lobbying Disclosure Act requires regular reports from individuals who make at least two lobbying contacts with covered government officials and who spend at least 20 percent of their time on lobbying activities for which they are paid. Grass-roots activism, most issue advertising and public relations work, even when part of an effort to persuade members of Congress, are exempt.