(AZCentral) - Call it the phantom rule. For years, Arizona wine consumers visiting small out-of-state wineries have heard that they may join the wine clubs, but they must trek back to the wineries at least once a year.

But that rule never existed, the state Liquor Department says. And though the rule's pervasiveness was acknowledged, no one knows how it came about.

Arizona Department of Liquor spokesman Lee Hill said Arizona customers can join wine clubs of out-of-state wineries, and that they need to be at the winery only once – when they sign up.

Hill said this has been the case for some time.

She said in an email that “previous” leaders of the state Liquor Department had allowed customers to join out-of-state wine clubs “without the requirement to physically visit the winery each time," adding, "The Department has continued this allowance to prevent any disruption in the industry.”

Members of wine clubs agree to buy a designated number of bottles each year from the winery, usually a selection curated by the winery. These can include small-production wines that aren’t on sale to the public. Wine-club members also get discounts.

State liquor statues allow a customer at an out-of-state winery to have up to two cases of wine shipped back to Arizona if they are “physically present” at the winery.

But the law also says that all wine must be purchased while the customer is there, something that would make joining a wine club problematic. Wine-club members typically pay for their wines when each shipment comes. The state Liquor Department’s “allowance” makes the agreement to purchase wine in the future count under state statute, Hill said.

The department let wineries know about the supposed rule, or lack thereof, through an advisory posted on its website in November 2014, and through training, Hill said.

However, that advisory did not explicitly mention wine clubs.

The rule appears to have also been enforced sporadically at some out-of-state wine clubs. An Arizona Republic reporter who is a member of two California wine clubs called and asked whether a member needed to come back and touch base each year. Each of the wineries said that was not required. Both said they remembered it being a requirement for Arizonans in the past, but didn't remember the origin of that rule.

But that non-existent rule was prevalent enough that an attorney for the Goldwater Institute, Clint Bolick, sent a letter to the Liquor Department in 2012 asking about the statutory justification for the rule.

In the letter, Bolick asks about a state statute that says a customer must be “physically present” at the winery to get wine shipped.

“We are informed that the Department interprets this provision to require that a purchaser must be physically present in each calendar year in which wine is shipped,” his letter said.

Bolick’s letter said that rule essentially meant few people could join out-of-state wine clubs. “A requirement of annual presence also does not serve any obvious public purpose,” he wrote, “given that the purchaser has established age and identity at the time of the order.”