I imagine a scenario like the following: Someone named Bob moves out of California, and establishes residence in another state. A few years later, he gets notice that California has taken a lien on his house and his car, and garnished his wages. While trying to figure that out, he discovers his bank accounts have been closed, and all his liquid assets seized by California's Franchise Tax Board. He gets a tax lawyer.
The tax lawyer finds out the following: Because Bob never filed the moving away paperwork, the Franchise Tax Board assumed Bob was still a California resident. When the FTB did not receive tax filings from Bob for the past 3 years, they assumed he was still making income and assessed a tax liability identical to the last known one. Then, after 3 years of assessing his taxes for him and not receiving payment, FTB sends Bob's case to their collections group, who discover he's now living in Minnesota. A move-out tax is added to Bob's case, and at the penalty rate because he did not inform California he was leaving. These assessed taxes sat, unpaid, until FTB's collections entered a case in California state court, requesting a judgemnt against Bob. Bob never got notice of any of this, because all the correspondence, including process serving, was all going to his last known address in California. When Bob didn't show up to court over these taxes, the court entered a default judgment against him, allowing FTB to enter their liens, garnish his wages, and seize all his liquid assets.
Bob and his lawyer rightfully agree that this is total bullshit, and sue California in federal court. The Federal District of California, is of course controlled by California politics and rules the following: California has the power as a state to levy taxes per the legislative processes established in the state constitution. The assessment of tax liability based on assumed income in the face of unfilled taxes, and the move-away tax were passed according the legislative process. Therefore, the taxes are legitimate. Further, Bob did not show up for court, therefore the default judgement and consequent liens, garnishments, and seizures are valid. That Bob never got notice is his fault, because he failed to follow California law and notify FTB of his change of address. Case dismissed.
Undeterred by the District Court's bullshit reasoning, Bob appeals up to the 9th Circuit. The 9th Circuit is again, largely controlled by California's politics, and upholds the district court's ruling. Bob appeals to the Supreme Court.
I can only hope that the Supreme court would rule that California has no power to make up income to assess taxes on, to assess taxes on income that happens outside the state, and that a move-out tax is an infringement on the freedom of movement protected by the US Constitution, striking down those taxes, and ordering California to release their liens, garnishments, and return to Bob all of his assets.