Although the US Supreme Court is allegedly non-biased and supposed to look at each case it rules on by the legal ramifications of each case, each member of the Court is a human being, and it is a given that human beings act and react upon their own beliefs and desires.

So it develops that sometimes we have a liberal court and sometimes, like now, sometimes we have a conservative court. Each member is brought in by the president currently in office, subject to ratification by the legislature at the time, a legislature also either predominantly conservative or liberal at the time.

Turnover of Supreme Court members is slow, since tenure is either life long or terminated only by a member's own decision to retire.

Currently we have a conservative Court, and their decisions reflect this, often by a 5 to 4 vote.

This won't change any time soon.