DENVER — Let’s say you’re playing poker and you need one more diamond for a flush. The dealer turns a card, reveals a diamond and you win the hand. Was it skill or luck?

The answer is affecting the fates of people across the country accused of breaking anti-poker laws — people like Kevin Raley, 44, of Colorado.

As an engineer, Raley finds the mathematics of poker come easily, and he’s pretty good at keeping a blank face. Reading other people, though, is something he’s always working on. “It’s something I’m better at today than I was five years ago,” said Raley.

This goes to the point Raley is trying to make: The better he gets, the more he wins.

Arrested a year ago for running a $20 buy-in Texas Hold ’Em tournament at a bar in Greeley, but acquitted by a jury, Raley now hopes to convince the Colorado Supreme Court of what he says is obvious to anyone who really knows the game — that poker hinges more on skill than chance.

Poker, especially Texas Hold ’Em, has exploded in popularity in recent years, with professional tournaments earning television coverage and major players fan followings.

Tolerated elsewhere

Most states generally tolerate poker as legal as long as it’s confined to games among friends in which no one makes a profit other than players. In Colorado, it’s illegal to participate in a game in which rake — or a commission fee charged by the poker operator — is taken.

It’s also one of 37 states where a game of skill doesn’t constitute gambling, said Chuck Humphrey, a Colorado-based lawyer and expert in gambling laws. (But California law, for example, doesn’t distinguish between skill and chance. It bans some games, such as faro and monte, but does not single out poker.)

At his January trial in Colorado, Raley argued that not only was poker a game of skill, but that it had been a game among friends. Prosecutors maintained that it was neither.

In a review of Raley’s case this month, a judge said poker relies heavily on chance. “A poker player may give himself a statistical advantage through skill or experience, but that player is always subject to defeat when the next card is turned,” Weld County District Judge James Hartmann wrote.

Tim Ouellette, of Greeley, disagrees. Ouellette, 46, of Greeley, was arrested along with Raley, but charges against him were dismissed following Raley’s acquittal. “It’s not like roulette or craps where you throw the dice and you have no control over it,” Ouellette said.

Raley is now petitioning the Colorado Supreme Court to weigh in on the question of skill versus luck.

Other recent skirmishes include a South Carolina case in which five men were arrested in a 2006 raid on a game of Texas Hold ‘Em. They were convicted this year by a municipal court judge who said he agreed that poker hinged on skill but felt it wasn’t clear whether that was relevant under state law. The men are appealing.

In Pennsylvania’s Columbia County, a judge dismissed charges in January against a man accused of running a poker game out of his garage, ruling that he hadn’t committed a crime because when skill predominates, it’s not gambling.

But in a second case in Pennsylvania, a Westmoreland County jury last month rejected a man’s contention that the Texas Hold ’Em tournaments he hosted in local fire halls were legal because they were games of skill.

The recent spate of trials represent a “radical break with the way poker cases have been handled before,” according to Nelson Rose, a law professor at Whittier Law School in California and a gaming industry consultant.

Unlike previous trials about poker, Rose says, defendants now are receiving financial and legal support from groups like Washington-based Poker Players Alliance, and judges are permitting testimony about research concluding that poker depends on skill.