SEATTLE (AP) — Former Washington Attorney General Rob McKenna has filed a lawsuit seeking to strike down the state’s new capital gains tax, arguing it is an illegal income tax. The Seattle Times reports the lawsuit, filed Thursday in Douglas County Superior Court, was brought on behalf of state residents including manufacturing business owners, investors, and the Washington State Farm Bureau. It’s the second such lawsuit filed challenging the new tax. The state Legislature this year passed a capital-gains tax meant for the state’s wealthiest residents. The measure adds a 7% tax on capital gains above $250,000 a year, such as profits from stocks or business sales.