Supreme Court justices cannot conduct hearings the way the Senate and the House of Representatives do both at the federal and state levels, they don't read constituent mail, they don't go out and visit people or inspect factories or inspect work sites or inspect abortion clinics. They're not allowed to talk about their cases with anyone other than their law clerks. They receive information only in a very limited and stylized way. The parties to each case are permitted to file a 50 page opening brief and a 30 page reply brief, which the justices and their law clerks read, and then typically each side to a case is allowed to orally argue its case for a half an hour, one hour total per case. Then the justices decide the case. This is a very narrow focused way of receiving information. It's a way of receiving information that's perfectly appropriate for a court that is interpreting text according to their original public meaning and enforcing them against statutes that violate those constitutional texts, but it's not a form of information gathering which is sufficient to make good public policy.