The Colorado Symphony Orchestra may rethink its plans for headline-grabbing, bring-your-own-pot performances after Denver city officials Thursday delivered a major buzzkill.

In the city’s view, the trio of fundraising concerts risk violating state and city laws barring public consumption of marijuana. The series, scheduled for the Space Gallery in Denver’s Art District on Santa Fe, will kick off May 23.

A hand-delivered letter prepared by city attorneys, along with licensing and police officials, urges the CSO to cancel the concerts. But it doesn’t stop there.

Should the orchestra ignore the city’s instructions, the letter says, “We will exercise any and all options available to the city of Denver to halt the event and hold the business owners (and) event organizers responsible for any violations of law.”

Those options include potentially denying special-event permits that are under consideration for the first two performances.

The city’s stance has the CSO reviewing its plans, announced last week, for “Classically Cannabis: The High Note Series.”

The CSO said in a statement that it “takes the issues raised by the city of Denver very seriously.”

“We’re reviewing the issues with our legal team,” the CSO said. “When the Colorado Symphony accepted support from the legal cannabis industry — as a means of supporting our financial operations and connecting with a culturally diverse audience — we believed we did so in full compliance with the law.”

Addressed to CSO president Jerry Kern, the letter was signed by Stacie Loucks, director of Denver’s Excise & Licenses Department.

The other two concerts in the “High Note Series” are set for July 18 and Aug. 15. CSO has also announced plans for a large, outdoor performance at Red Rocks Amphitheatre on Sept. 13, but that venue bans marijuana consumption. The city’s letter doesn’t address the Red Rocks concert.

The city’s intervention echoes a public fight this year with organizers of the 4/20 festival in Civic Center park. After asking the city to sanction public smoking of pot at the event — Mayor Michael Hancock and other officials balked — 4/20 organizers backed off and publicized that it wasn’t allowed at last month’s event.

A difference in CSO’s case is that its Space Gallery concerts are planned for a private venue. Plans call for having a smoking lounge on an enclosed outdoor patio.

But the city’s letter argues that the Space Gallery “may be considered a public place under Colorado law,” and it also cites provisions from voter-approved Amendment 64, which legalized pot possession and private consumption; the state’s anti-smoking law; and city ordinances regulating retail cannabis licenses.

It’s adapted from a form letter the city has sent often to urge promoters to call off marijuana-related events, large and small, that might run afoul of marijuana laws. City Attorney Scott Martinez said most agree to call off events.

Sam Kamin, a University of Denver law professor, said the city’s case is more sound for an obviously public event such as 4/20 than for events at private venues.

But it hasn’t yet been tested in court.

If the plan is for pot consumption to be confined to a patio at the Space Gallery, Kamin said, “that sure looks more private than public” to most people.

“If the symphony decides to make a test case of it, it would be more interesting,” he said. “It would be a much closer case than the Civic Center event would be.”

Edible Events owner Jane West, who lined up lead sponsor Ideal 420 Soils and two dispensaries to support the CSO series, declined to comment Thursday about the city’s letter.

The CSO’s plans drew international attention, along with a few jokes from late-night TV hosts.

The orchestra’s aim was to expand its reach and raise money. Attendees were asked to donate $75 minimum to hear small ensembles of musicians, taste gourmet food, and drink wine and beer.

Jon Murray: 303-954-1405, jmurray@denverpost.com or twitter.com/denverJonMurray