The city police and the county prosecutor in Seattle thought they had an understanding: The prosecutor assumed the cops wouldn't be busting pot delivery services for felony weed sales. The cops assumed they could.

So they did, spending a day last month posing as buyers and then arresting the runners who brought them weed for sale, a service that remains outlawed despite a law passed in 2012 that allows adults over 21 to purchase pot for recreational use at state-regulated stores.

The suspects all walked free, following a stern rejection of the police actions by the prosecutor. The bust-buy sting at a rented north Seattle motel room on April 5 was "unwarranted, disproportionate to the harm caused, and would have little or no impact on the delivery business in Seattle," wrote King County Prosecuting Attorney Dan Satterberg in a letter to police obtained by VICE News. "Consequently, I decline to prosecute."

The police chief took exception, telling the prosecutor, "We need to send a message that black market sales will not be tolerated."

For the moment, there is a detente between the two sides, but still no resolution on how the city can best control the illegal delivery of cannabis. City officials have identified at least 24 different companies offering weed delivery — even though Seattle only has 19 licensed recreational marijuana shops.

"These services provide an outlet for marijuana grown by criminal organizations while undermining the legal industry," the city said earlier this year, noting that the businesses aren't paying the state's steep taxes on legal weed, and peddling their product with no oversight on sales to minors or pesticide use in the growing process.

'The result of this operation was to arrest and book a few individuals at the end of the supply line.'

The problem isn't limited to just Washington. Three other states — Colorado, Oregon, and Alaska — plus Washington, DC now have laws that permit recreational marijuana use by adults. None currently permit pot delivery, but the services are increasingly common. Other states, including California, allow medical marijuana to be delivered, and some companies have developed apps that let customers use smartphones to place orders that are guaranteed to arrive in an hour or less.

Seattle Mayor Ed Murray and City Attorney Pete Holmes pushed a bill earlier this year in the state legislature that would have created a pilot program for legal marijuana home delivery service in Seattle. The proposal to create what was dubbed "Uber for pot" failed to pass, however, leaving a dilemma: Can the state stamp out the weed black market through legalization and regulation without catering to the demands of consumers? And if cops aren't allowed to bust pot delivery services, what's stopping them from continuing to operate?

The day-long operation by Seattle police nabbed seven runners from a half-dozen services easily reached by phone or online, such as Bud Lady and Mr. Green Jeans. Once the suspects arrived with the goods and police completed the buys — worth $150 to $260 each — the runners were arrested, handcuffed, and taken to jail.

Though the cops failed to consult the county prosecutor about the operation, other Seattle officials have publicly called for a crackdown on the delivery services.

"Businesses that currently deliver marijuana undermine our efforts to demonstrate that there is a regulatory alternative to marijuana prohibition," said Holmes, the city attorney, in a statement issued in January. "All current delivery services are engaged in nothing less than the felony distribution of a controlled substance and must be closed."

The mayor's office has said previously that such a crackdown could also help keep the feds at bay. In 2013, after Colorado and Washington voted to legalize recreational marijuana, then-Deputy Attorney General James Cole issued a memo to federal prosecutors across the country that said if local governments regulate pot businesses in a way that addresses federal priorities, interference would be unlikely. So far, the Department of Justice has kept its word. But if delivery services are caught selling to kids or violating other guidelines spelled out in what's now known as "the Cole memo," the feds might feel motivated to shut down the illegal and voter-approved recreational sales operations.

Watch the VICE News documentary Inside America's Billion-Dollar Weed Business: The Grass Is Greener

But in Satterberg's April 12 letter to the Seattle police narcotics unit, the county prosecutor said the buy-bust tactic was not the best way to go after the delivery services. He noted that the sting "targeted the lowest-level employees" and pointed out that a softer approach has been used to effectively shut down unlicensed dispensaries in the area.

"It is not clear who owns the delivery service or profits from the sale of unregulated marijuana," Satterberg said, adding that "the result of this operation was to arrest and book a few individuals at the end of the supply line."

There had been "no outreach" by police to prosecutors about the sting, he wrote. Conversely, he said his office had been working for nine months with the county sheriff to close down 15 unlicensed retail sales operations in the suburbs.

Thanks to a change in the law, and the threat of civil lawsuits being brought by the county against the businesses, the problem was solved, said Satterberg. "No arrests were made and no criminal charges were filed, but the businesses have all closed."

Seattle Police Chief Kathleen O'Toole wasn't satisfied with the explanation, however. Her review of the delivery service sting found that in at least four cases, the subjects arrested were not low-level employees.

'These services provide an outlet for marijuana grown by criminal organizations while undermining the legal industry.'

"These suspects possessed significant amounts of marijuana, up to two pounds, and a wide selection of marijuana products," she wrote in response to Satterberg. "At least one suspect carried Oxycodone, which amplifies our anecdotal information that these delivery services may include delivery of drugs other than marijuana."

One of those arrested admitted the weed he was selling was grown under his medical marijuana authorization. He made up to four sales daily. He thus was an "owner-operator," the chief said, not a low-level runner.

But typically, the chief wrote, investigating such cases usually means getting reluctant suspects to talk. And without a credible threat of prosecution, "it is unlikely that suspects will cooperate with law enforcement."

O'Toole added that, "I want to underscore how much I value our professional friendship and the strong partnership between the SPD and your office." But she hoped Satterberg would reconsider filing the felony charges.

Leesa Manion, Satterberg's chief of staff, said that "since the exchange of letters, Chief O'Toole and Dan have had a conversation and have agreed to meet to discuss this issue further. That meeting has not yet been scheduled, but will be in the very near future."

In the meantime, a visit to the websites Leafly and Weedmaps, which track local dispensaries and other marijuana-related products and services, shows that a number of distributors are still delivering orders in the Seattle area despite the recent police crackdown. Several customers left enthusiastic reviews, indicating that authorities likely face an uphill battle if — or perhaps when — they try again to shut them down.

"My delivery was quick, exactly what I expected," one user wrote of the service Supreme Green Delivery. "The staff member that met with me was courteous and friendly, I felt totally at ease. I cannot believe in my lifetime that it was/is this simple and such an enjoyable experience."