@WilhelmIII @BattleDwarfGimli @KennyWhitePowers @Rose @bobbala @feralphilosophernc @jb @lovelymiss @Escoffier @Liquid_Boss @Spingebill @UnCL3 @dictatordave @graf Article 3 section 1 gives the SCOTUS the judicial authority to be the final say in all matters of legal interpretation and constitutional compliance challenges.

Which is to say that if a challenge to a court packing was brought before them, they could intervene using Stari Decisis.

When you look, up until the Civil War, the number was simply based on the number of circuit courts there were in the US. It seems to get more political as time went on after that, but "court packing" was seen as a bad thing and a power grab, and the label was used to defeat Presidential efforts to change the balance of power in the courts.

But yes, it looks like if a President wants additional judges and Congress can bring a vote, bypass filibuster in the Senate, and pass legislation to do so, then it could be done. And, once done, the court could intervene if a challenge was brought against the law. I don't see the number of judges changing any time in our lives.