If Cinco de Mayo isn't enough reason for some Utah revelers to party, consider this: The amount of liquor allowed in the standard cocktail is increasing by 50 percent to 1.5 ounces.

The first major change to state liquor laws in years will take effect Monday as part of an effort to improve the state's teetotaling image and appeal to more tourists around the world.

Utah has some of the nation's strictest liquor laws and weakest drinks. It is the only state that caps how much alcohol can be served in a shot or a cocktail, according to the National Conference of State Legislatures.

Tourists "complain about the size of the martinis and the cost of everything," said Matthew Kallio, a bartender at a downtown hotel.

By allowing up to 1.5 ounces of liquor, Utah's drinks will be more in line with the industry standard.

But if there ever was a day that could illustrate how convoluted and quirky the state's liquor laws remain, it could be on the holiday that celebrates Mexican troops' defeat of a French army on May 5, 1862.

Traditionally, Mexican beer, margaritas and tequila are the drinks of choice at many bars on Cinco de Mayo.

But if anyone in Utah has an unfinished margarita on the table or bar Monday, ordering an accompanying shot of tequila will be illegal.

The rule will apply to all cocktails — ordering a shot of the same liquor that's already in your drink is impermissible. All other liquor is fair game. Servers must keep track of the primary liquor in everyone's drink before serving a round of shots.

Bar owners are already pondering the legal gymnastics that customers and servers are about to perform along with windy explanations of Utah's new law.

"There's ways around it, but it makes absolutely no sense whatsoever," said Dave Morris, owner of Piper Down: An Olde World Pub in Salt Lake City.

"That's what's the really, really messed up part of this whole thing. Say you do order a margarita, which we'll make with Jose Cuervo, and then you want a shot of tequila. You can do it, you're just going to have to order a different shot ... say a shot of Patron."

Utah's liquor laws have left tourists scratching their heads in confusion for decades.

However, resident drinkers and frequent visitors have learned to navigate them so well that increasing the amount of booze in the standard cocktail is actually an attempt by lawmakers to reduce consumption.

Currently, the amount of liquor allowed in a shot or cocktail is 1 ounce. An additional 1.75 ounces of liquor considered "flavoring" is also allowed in some drinks.

Customers can order a second shot known locally as a "sidecar" they can take in one gulp our pour into their drinks as long as the total amount of alcohol doesn't exceed 2.75 ounces. Asking for a double and having a bartender pour it is illegal.