India has a single integrated judiciary with the Supreme Court at the top, High Courts in the states and subordinate courts below. Judges of the Supreme Court are appointed by the President and retire at 65; High Court judges retire at 62.
The Supreme Court has original, appellate and advisory jurisdiction. Judicial review lets it strike down laws that violate the Constitution, and public interest litigation has widened access to it considerably.
The basic structure doctrine, laid down in the Kesavananda Bharati case, holds that Parliament cannot amend the essential features of the Constitution.