Historically it has not been unanimous: https://news.bloomberglaw.com/us-law-week/supreme-court-unanimity-is-fleeting-with-tougher-cases-looming-37 https://news

Historically it has not been unanimous: https://news.bloomberglaw.com/us-law-week/supreme-court-unanimity-is-fleeting-with-tougher-cases-looming-37 https://news.bloomberglaw.com/us-law-week/supreme-court-unan... And as the article says the courts have been increasingly looking at narrowly scoped cases that are less precedent changing.