Washington state vows to try to keep weed in state—but how?

SEATTLE—So far, no one is suggesting checkpoints or fences to keep Washington state’s legal pot within its borders.

But Gov. Jay Inslee insists there are ways to prevent the bulk smuggling of the state’s newest cash crop into the black market, including digitally tracking weed to ensure that it goes from where it is grown to the stores where it is sold.

With sales set to begin later this year, he hopes to be a good neighbor and keep vanloads of premium, legal bud from cruising into Idaho, Oregon and other states that don’t want people getting stoned for fun.

It’s not just about generating goodwill with fellow governors. Inslee is trying to persuade U.S. Attorney General Eric Holder not to sue to block Washington from licensing pot growers, processors and sellers. Marijuana remains illegal under federal law.

“I am going to be personally committed to have a well regulated, well disciplined, well tracked, well inventory-controlled, well lawenforcement-coordinated approach,” said Inslee, who expects to give Holder more details by next week.

Keeping a lid on the weed is just one of the numerous challenges Washington state authorities and their counterparts in Colorado—where voters also legalized pot use—will face in the coming months.

The potential of regulatory schemes to keep pot from being diverted isn’t clear. Colorado already has intensive rules aimed at keeping its medical marijuana market in line, including the digital tracking of cannabis, bar codes on every plant, surveillance video and manifests of all legal pot shipments.

But law enforcement from Colorado’s officials say dispensaries marijuana often makes its way to the black market, and even the head of the Colorado agency charged with tracking the medical pot industry suggests no one should copy its measures.

The agency has been beset by money woes and had to cut many of its investigators. Even if the agency had all the money it wanted, the state’s medical pot rules are “a model of regulatory overreach,” too cumbersome and expensive to enforce, Laura Harris said in a statement.

Associated Press This photo taken Saturday shows a bar code attached to pots growing marijuana plants at a grow house in Denver. The bar codes are assigned to each plant and follow it through the growing and distribution process. Washington state is considering the use...