Amendment & Miscellaneous
(1) Despite the Constitution repealing certain enactments (Article 395), all pre-existing law in India continues in force until altered/repealed/amended by a competent Legislature/authority. (2) The President may, by order, adapt/modify such laws to bring them into accord with the Constitution. (3) This adaptation power expired 3 years after the Constitution's commencement, though competent Legislatures can still separately amend such adapted laws afterward.
This is the master continuity provision that prevented India's entire pre-existing legal system from suddenly evaporating on 26 January 1950 - all the laws that existed the day before the Constitution took effect continued operating, with the President given a temporary (3-year) power to tidy up any inconsistencies between old laws and the new constitutional framework.
This is why many laws that predate India's independence (like parts of the Indian Penal Code, 1860, or the Indian Contract Act, 1872) continued in force after 1950 and remain in force today - the Constitution's arrival didn't wipe the legal slate clean, it built continuity into the transition.