The Washington Supreme Court heard arguments Tuesday on whether timber owners and loggers can be sued if trees left standing to benefit the environment fall and cause damage.

The main defendant, the Department of Natural Resources, argues state law grants forestland owners, including itself, immunity because trees that fall naturally along creeks help fish and water.

A man grievously injured by a falling tree argues DNR forfeited that immunity with a poorly planned timber harvest that endangered public safety.

The Washington Farm Bureau and timber industry are asking the court to side with DNR. Without immunity, landowners will be encouraged to cut every tree possible, according to their friend-of-the court brief.

“That is bad land stewardship and bad public policy,” the brief reads.

The case stems from a timber harvest on DNR land in Snohomish County in 2018. DNR told loggers to leave a sliver of trees in a “riparian management zone” wedged between a creek and road.

The logging operation was wrapping up when a 120-foot tall Douglas fir uprooted in a windstorm and crashed on a Ford Explorer driven by Snohomish County Public Utility District employee Barry Chrisman.

Chrisman spent 117 days in a hospital and is permanently disabled. The PUD and Chrisman allege that DNR ignored the warnings of its biologist that leaving a narrow strip of wind-exposed trees was dangerous.

According to court records, a logger videotaped Chrisman’s crushed vehicle and profanely commented: “This is what happens when you cut tall trees and leave a border along the (bleep) road like this. PUD guy just got smashed and is heading out in the (bleeping) ambulance. Look at all this (bleep). The whole (bleeping) patch blew over (and) smashed him.”

Besides DNR, the PUD and Chrisman sued the timber buyer, Sierra Pacific Industries, and logging subcontractor Precision Forestry, though neither private company was involved in deciding which trees to leave.

The tree was 227 feet from the creek and at least 22 feet beyond what should have been by state rules the edge of the riparian management zone, according to expert testimony presented by the PUD.

Because it mismeasured the zone, DNR should not have immunity, the PUD argues.

A Snohomish County Superior Court judge dismissed the lawsuit, ruling that even if the zone was wrong, immunity applies to all trees left standing in order to reap the environmental benefit.

An appeals court overturned that decision. Sierra Pacific and Precision Forestry can be sued because only landowners are immune, and DNR can be sued for cutting down trees that exposed the standing trees to wind, the three-judge panel ruled.

The ruling greenlights lawsuits against landowners for either cutting down too many wind-blocking trees or too few wind-exposed trees, according to the Farm Bureau and timber industry.

The Washington Forest Protection Association, American Forest Resource Council and Washington Farm Forestry Association are among the other groups that signed the friend-of-the-court brief.

Without immunity, timber companies will be reluctant to log near riparian management zones, hurting the industry and its workers, according to a brief filed by Sierra Pacific.