Contrary to our idealized expectations, the Supreme Court largely appears to work the way Richard Posner claims it does. The justices figure out what they want the outcome to be, then they interpret the law to justify that outcome, unless the prevailing law makes it brazenly ridiculous to do so. Because law is composed of words, and words are vague and open to multiple interpretations, a huge space exists for judges to act as political legislators — and they do.
So what does that leave us? A Supreme Court that is an eminently political institution whose composition is at best random and at worst a function of strategically timed retirements. This makes no sense and needs to be reformed.
The best reform proposal I’ve seen is the brainchild of law professor Paul Carrington. Under his proposal, Supreme Court judges would serve single, staggered 18-year terms, such that a new judge would be appointed every two years. This fixes the issue of randomness, which can create huge judicial windfalls for certain presidencies. It also fixes the strategic retirement problem, since judges would be forced out after 18 years.
Furthermore, it allows the court to change in line with the political tides of the country. The ideological composition of the court at any given time should generally mirror that of the presidency in the 18 years prior.