“Brennan liked to greet his new clerks each fall by asking them what they thought was the most important thing they needed to know as they began their work in his chambers,” Seth Stern and Stephen Wermiel write in “Liberal Champion,” their Brennan biography. “The … stumped novices would watch quizzically as Brennan held up five fingers. Brennan then explained that with five votes, you could accomplish anything.”
Brennan, master vote-counter and vote-cajoler, was right — but there is an important corollary to his famous Rule of Five, one powerfully at work in the current Supreme Court. That is the Rule of Six. A five-justice majority is inherently fragile. It necessitates compromise and discourages overreach. Five justices tend to proceed with baby steps.