WASHINGTON — Since December, when President Bush signed a new forestry law, the government has won 17 straight court cases favoring timber cutting over environmental interests.

Bush pushed for the law that sponsors named the Healthy Forests Restoration Act, saying it would reduce wildfires in national forests by thinning trees while also limiting appeals and environmental reviews.

Environmentalists say the new law has undercut important protection for old-growth trees and remote, roadless areas.

In a memo obtained by The Associated Press, the Agriculture Department's general counsel, Nancy Bryson, touted the Forest Service's success in winning all 14 court cases in March.

Asked about the memo, Mark Rey, the Agriculture Department undersecretary who directs U.S. forest policy, said, ‘‘Any month when you win 14 out of 14 cases is a good month.''

Since then, the agency has won at least three more cases without a loss, officials said Thursday.

The court victories mark a turnabout from recent years, when environmentalists succeeded in delaying and halting logging projects that the Bush administration and many Western lawmakers said could have removed the trees and underbrush fueling wildfires.

Rey, however, stopped short of declaring victory.

Court challenges ‘‘are still taking up a lot of time,'' he said. ‘‘Every one of these lawsuits was a delay in getting a project started. But what I think we are getting is, finally, some consistent direction from the courts that they want this work done too.''

Environmentalists said the Forest Service's winning streak would be more impressive if the law had not been changed to favor the administration's approach.

If the new law ‘‘is now making it harder for people to challenge timber sales, then that is exactly what everyone was worried about,'' said Kristen Boyles, a lawyer for Earthjustice, an environmental group that has challenged many of the administration's tree-cutting projects in court.

‘‘It's no secret that environmentalists think ‘healthy forests' is misnamed,'' Boyles said. ‘‘It's not about healthy forests, it's about getting out the cut.''

The law authorizes up to $760 million a year to treat up to 20 million acres of federal forests and grasslands at risk of catastrophic fire. At least half the tree-cutting on that land has to be concentrated in areas near homes and communities.

Judges are required by the new law to weigh the environmental consequences of inaction — and the risk of fire — in considering tree-cutting projects. And any court order blocking such projects must be reconsidered every 60 days.