The Alliance for the Wild Rockies on Tuesday filed a lawsuit in federal court to force the U.S. Fish and Wildlife Service to upgrade federal protections for grizzly bears in the Cabinet-Yaak ecosystem.

Grizzlies in the lower 48 states have been listed as “threatened” under the Endangered Species Act since 1975. One of five distinct populations, the bears in the Cabinet-Yaak ecosystem have struggled compared with the populations occupying areas near Glacier and Yellowstone national parks.

The Missoula conservation group’s lawsuit alleges that the Fish and Wildlife Service failed to use a scientific rationale in its 2014 decision not to reclassify the Cabinet-Yaak population as “endangered.”

The lawsuit states that internal documents show that the decision was instead intended to render a 2014 lawsuit against the agency moot.

“The population of Cabinet-Yaak grizzly bears is simply not recovering,” Michael Garrity, the organization’s executive director. “Instead, mortalities are increasing and the population is likely dropping.”

The Fish and Wildlife Service in 1991 concluded that the population warranted an “endangered” listing, but in 1993 issued an order that the uplisting was “warranted but precluded.” The agency issued a similar decision in 2013, prompting Alliance for the Wild Rockies to sue in 2014.

Later that year, the Fish and Wildlife Service found that the listing was not warranted, citing improvements in the population trend from “declining” to “stable.”

The suit also alleges that the agency has maintained the bears’ “threatened” status to avoid delineating critical habitat, which was not required at the time of the original listing.

Recent estimates of the Cabinet-Yaak’s grizzlies have been at or less than half of the target recovery population of 100 bears. A report in 2012 estimated 45 bears occupying the region.