The problem is that existing law in many cases (that end up in SC) is simply too vague to be a meaningful expression of intent. In those cases, since the judges are still required to rule one way or another, we end up getting those tortured decisions where a big effort is made to contort the law into some interpretation that would allow for a ruling.

In my opinion, if SCOTUS is split 5/4 (or even 6/3) on anything, that should be taken as prima facie evidence that the law is unclear and needs amending. At that point we should require all the deciding judges to make a write-up for each opinion in the case detailing the requisite changes to the law that would make all judges to rule unanimously in favor of that opinion. These can then be submitted to the legislature or a referendum or whatever, but either way some decision needs to be made.