To the best of my knowledge, unless a justice has recused themself from a case, they can vote on a case. There is an article below regarding the Notorious RBG continuing to participate while recovering at home from January 7, 2019.
https://apnews.com/article/Ginsburg misses Supreme Court arguments for the 1st timeWASHINGTON (AP) β Justice Ruth Bader Ginsburg is missing arguments for the first time in more than 25 years as she recuperates from cancer surgery last month, the Supreme Court said.
Ginsburg was not on the bench as the court met Monday to hear arguments. It was not clear when she would return to the court, which will hear more cases Tuesday and Wednesday, and again next week.
Court spokeswoman Kathy Arberg said the 85-year-old justice is continuing to recuperate and work from home after doctors removed two cancerous growths from her left lung on Dec. 21.
Ginsburg was discharged from a New York hospital on Dec. 25.
Chief Justice John Roberts said in the courtroom Monday that Ginsburg would participate in deciding the argued cases βon the basis of the briefs and transcripts of oral arguments.β
Ginsburg did not return to the court until February 19th after being absent for two months, but decided on 11 cases while recuperating at home.
https://www.npr.org/2019/02/19/695773628/ruth-bader-ginsburg-returns-to-supreme-court-bench-after-lung-cancer-surgeryThe 85-year-old liberal feminist icon underwent surgery for lung cancer in late December and since then has been recovering at home. In January, for the first time in her 25-year tenure, she missed being in court for oral arguments, but she participated in the decision of those 11 cases based on the written briefs and transcripts of the arguments.