We have a Constitution, many a times the Constitution runs parallel to many laws which were enacted earlier to the Constitution coming into force. This includes many provisions including some of the sections under the IPC or the Evidence Act. Many of these things (laws), if put to acid test of the Constitution, they may not stand up to the scrutiny. This is the apprehension. Either the Constitution makers did not anticipate this situation or a review of the laws or the Constitution should have taken place for properly synchronising the two.
[The above is an approximate quote - readers can hear him speak in this video.]
But surely there is a third possibility--That the founders were well aware of possible conflict between colonial laws and constitutional morality, but left it for the courts and legislatures to gradually reform the former to bring them in line with the latter. This is what I had argued in an earlier opinion in the context of impunity provisions which are also colonial in origin:
Independence, when it came in 1947, marked the end of a colonial government, but it was only the beginning of the end of the colonial system of governance. This system is opaque rather than transparent, and seeks to control subjects rather than empower citizens. The accountability-seeking and empowering constitutional regime that came about in 1950 did not abolish this colonial system of governance outright. For pragmatic reasons, the constitutional design contained in Article 372 envisaged its gradual unravelling over the years.
This debate on the intention of the founders is interesting because the Supreme Court in Anuj Garg and the Delhi High Court in Naz Foundation [para 105] have suggested that colonial laws do not merit the presumption of constitutionality that is extended to post-constitutional laws.