Which of the following doctrines are not used in determining the legislative competence of Parliament and State Legislatures under Part XI and Schedule VII of the Constitution?

Correct option is C

The Doctrine of prospective over-ruling is used to ensure that judicial decisions apply prospectively to avoid unsettling past actions, but it is not relevant in determining legislative competence. The other doctrines—pith and substance, harmonious construction, and colourable legislation—are commonly applied for such determinations.