Robert Mahon was quoted several times in the Law360 article, "New Seattle Tax On Wealthy May Lead To Statewide Income Tax," regarding the possibility of a statewide income tax if Seattle's new tax on high-income households can overcome some significant legal hurdles.

Before addressing constitutional concerns, courts may first have to sort out statutory issues such as state law expressly prohibiting a city tax on “net income,” according to Robert Mahon.

“I expect [the city] to argue this is not a tax on net income,” Mahon said. “That leaves them with only, I think, one alternative, which is that it is a tax on gross income.”

However, if Seattle’s income tax can be classified as a tax on gross income, it would fail to meet “many of the state law” requirements for Business and Occupation taxes levied on gross income, Mahon said.

While Trump’s political agenda may be a motivating factor for Seattle to press forward with its ordinance, Mahon said that many people have viewed Washington’s tax policy for years as being regressive and advocated for an income tax long before Trump came on the scene.

“We’ve seen virtually every elected official in Seattle for years come out on the record as being in favor of a state income tax. I think it’s a broader policy and Trump is being used as convenient fuel,” Mahon said.