Amazon, Facebook, Google and a number of other internet giants are suing Maryland to stop the state from implementing a first-of-its-kind tax on online ads, calling the measure an illegal and “punitive assault” on digital advertising.

The lawsuit, which was filed Thursday in U.S. District Court in Maryland, comes just over a week after the Maryland General Assembly voted to override Gov. Larry Hogan’s veto of the bill creating the tax, which lawmakers approved last year.

The tax would apply to companies that sell the ads and make more than $100 million a year in revenue. The tax ranges from 2.5% to 10% per ad, depending on the value of the company.

Proponents say the measure would modernize the state’s tax code to reflect the changing economy and shopping habits, pulling in an estimated $250 million a year for Maryland’s public schools. Some also argued it would serve as a mechanism to regulate powerful internet companies that sweep up personal data and use it to craft targeted ads.

But critics, including the U.S. Chamber of Commerce and Internet Association — a trade group representing some of the internet’s most prominent companies — say in the lawsuit that Maryland lawmakers “disapprove of digital advertising companies and intend to penalize them.” They say the new tax will lead to a drop in high-quality ads and “raise costs for consumers and make it more difficult for businesses to connect with potential consumers.”

They also argue the tax violates a federal law prohibiting states from imposing “discriminatory taxes on electronic commerce,” and is unconstitutional. They are asking a federal judge to declare the tax illegal and stop Maryland from imposing it.

In a statement, Maryland Senate President Bill Ferguson lambasted the internet giants for filing suit.

“While unsurprising, it’s disappointing to see these companies spend millions on high powered attorneys instead of paying their fair share. For two decades, these companies have grown exponentially by availing themselves of the privileges of states, benefited from the aggressive uncompensated collection of personal and private information about Maryland’s residents, and been free riders to Maryland’s investments in our civic infrastructure. All of this while contributing nothing to the future of Maryland’s residents,” he said.

“House Bill 732 seeks to change this equation to promote economic fairness in a Constitutional manner. I have full confidence in the office of Attorney General [Brian] Frosh, and look forward to these corporations paying their fair share to help build a world class education system for all Maryland families,” he added.

Still, even Frosh warned that the bill could be on risky legal territory, saying last year that “there is some risk” that a court could strike down some provisions of the bill over constitutional concerns.