Churchill Downs Inc., operator of the TwinSpires.com online horse betting site, filed a suit in US District Court in Austin, TX last week challenging a Texas state law against Internet gambling that the company claims is unconstitutional.

According to an article in the Louisville Courier-Journal, the dispute arose after the Texas Racing Commission sought to enforce a law requiring horse betting to be done in person at the track. Churchill Downs business has been bolstered in recent years with the addition of online wagering, which now represents nearly a quarter of the company’s earnings.

Churchill’s argument is that the state ban violates the US Constitution’s Interstate Commerce clause. The lawsuit asserts “A state cannot impose an ‘in person’ transaction requirement on the purchase of shoes or books, for no reason other than to favor local businesses at the expense of out-of-state entities like Zappos.com or Amazon.com.”, and argues that the same scenario applies to betting.

The Racing Commission thinks differently, and their spokesman notes that eight other online wagering companies stopped operating in the state of Texas after they were sent cease-and-desist letters from the commission. As of now, TwinSpires.com is still accepting wagers from Texas residents.