California’s Legislature is considering a wealth tax on residents, part-year residents, and any person who spends more than 60 days inside the state’s borders in a single year. Even those who move out of state would continue to be subject to the tax for a decade—a provision that calls to mind the Eagles’ famous “Hotel California” lyric: “You can check out any time you like, but you can never leave.” The California Constitution probably allows a statewide wealth tax on residents, but any effort to create a tax capable of reaching across state borders is likely to run afoul of...