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Dick's Sporting Goods now faces lawsuits in two states — Oregon and Michigan — over its decision to stop selling guns to anyone under 21, a move done in response to last month's Florida school shooting.

Walmart, which announced a similar policy, faces an identical lawsuit in Oregon.

While the retailers say they have no plans to rescind their new policies nationwide, a lawyer involved in the court challenges says he expects to see more suits filed soon in other states.

In both Oregon cases, 20-year-old Tyler Watson of Gold Hill, went to the stores, tried to buy a rifle, and was told he couldn't because of the new ban on selling to anyone under 21.

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His lawsuits, filed March 5, claim the stores violated an Oregon law that bans discrimination by places of public accommodation on the basis of nine factors, including age. The law has a few exceptions, allowing for higher age qualifications to buy alcoholic drinks or marijuana and permitting special rates or service to anyone over 50. But there's no exception for firearms.

Related: 20-year-old sues Dick’s, Walmart over new gun policies

"I am confident that Walmart and Dick's are violating Oregon's discrimination in public accommodations laws," said Max Whittington, the lawyer who filed the challenges in that state.

"The wording of the statute only has one reasonable interpretation, and that is you cannot discriminate against 18-20 year olds in offering the sale of goods which they're legally allowed to purchase, be they rifles, or any other legal product," he said.

Eugene Volokh, a law professor at UCLA said the case "seems open and shut for the plaintiff and against Dick's."

Dick's Sporting Goods store Keith Srakocic / AP file

In the Michigan case, filed on March 6, an 18-year-old man was turned down when he tried to guy a rifle at a Dick's store in Troy. The state has a public accommodation law like Oregon's.

Fifteen other states have similar laws, banning age discrimination but making no exception for gun sales. Maryland, by contrast, prohibits age discrimination but also bans the possession of the most common assault weapons by most residents under 21.

Whittington said he expects that "a number of similar cases are going to be filed around the country."

But Laura Cutilletta, legal director of the Giffords Law Center to Prevent Gun Violence, said the same justifications for setting age limits for driving or drinking, including immaturity and impulsiveness, support limiting gun sales to the youngest customers.

"There is an actual scientific reason for treating young people differently when it comes to the purchase of a highly lethal product that has been used so many times to kill large and small numbers of people," she said.