Four months after voters in Colorado and Washington legalized limited marijuana possession and sales, the federal government remained resolutely mum Wednesday on what it will do about it.

In testimony before the U.S. Senate Judiciary Committee, U.S. Attorney General Eric Holder offered no new foliage for those reading the federal government’s tea leaves on marijuana.

“We are … at this point considering what the federal government’s response to those new statutes will be,” Holder said. “I expect that we will have an ability to announce what our policy is going to be relatively soon.”

That is, essentially, the same answer he gave last week to a gathering of state attorneys general, and it offered no update on President Barack Obama’s comment in December that “what we’re going to need to have is a conversation” on the discrepancies between state and federal marijuana laws.

Holder’s comments, though, came amid mounting pressure on the federal government to do something.

On Tuesday, a United Nations-affiliated drug agency scolded governments that allow a loosening of drug laws — a swat partially directed at the United States following the two states’ legalization votes. The same day, eight former leaders of the Drug Enforcement Administration urged Holder, in a letter, to file a lawsuit arguing that Colorado and Washington’s new marijuana laws are illegal and preempted by federal law.

But University of Denver law professor Sam Kamin, who served on Colorado’s recently concluded marijuana task force, says a federal lawsuit probably wouldn’t succeed in overturning the Colorado law. The federal government can’t force a state to make something — such as small-scale marijuana possession — a crime. And Kamin said Colorado’s new laws for marijuana sales aren’t so opposite of federal law that people can’t comply with both. In other words, Kamin said, the state law isn’t forcing anyone to sell pot.

“It’s quite easy for someone to obey both state and federal law,” Kamin said. “Don’t sell and grow marijuana.”

That possibly explains the state of arrest the Department of Justice currently finds itself in.

Marijuana advocates, though, are optimistically suggesting a different explanation: Perhaps, by not commenting as regulations for recreational marijuana proceed in Colorado and Washington, the federal government is giving a winking approval.

“We’re glad to see a dialogue taking place between state and federal officials,” said Mason Tvert, one of the chief proponents of marijuana legalization in Colorado, “so that we can arrive at a solution that respects voters in these states as well as federal interests.”

John Ingold: 303-954-1068, jingold@denverpost.com or twitter.com/john_ingold