From 2004:
Although he is confined to his house for the time being, Rehnquist can still participate in Supreme Court decisions. Justice John Paul Stevens, who is subbing as chief justice with Rehnquist gone, made this clear yesterday when he commented that his cancer-stricken colleague “reserves the right” to cast his vote in upcoming cases. That includes cases for which the chief justice isn't physically present for oral arguments; he will rely on transcripts and written briefings instead
http://www.slate.com/articles/news_and_politics/explainer/2004/11/what_happens_in_ascotus_tie.html
these people are so important w need to squeeze every ounce of life out of them
no one is indispensable