This is an interesting question which forms the basis of the argument of those who oppose hudud. The Federal Constitution is the supreme law of the land of Malaysia. Any law which is in conflict with it is null and void

Article 8(1) of the Federal Constitution states that, “all persons are equal before the law and entitled to the equal protection of the law.” So in order to implement hudud, the Federal Constitution needs to be amended. Sounds easy enough?

There’s a catch though. There’s something called a basic structure doctrine. “The basic structure doctrine is an Indian judicial principle that the Constitution of India has certain basic
features that cannot be altered or destroyed through amendments by the parliament . Key among these “basic features”, are the fundamental rights granted to individuals by the constitution” (as per www.wikipedia.org/Basic_structure_doctrine)

Now you may wonder, since the excerpt says that it’s an Indian judicial principle, does it bind Malaysia? The case of Loh Kooi Choon v. Government of Malaysia established that the basic structure doctrine is also applicable to Malaysia’s Constitution. The decision concerning the “basic structure” of the
Constitution in Loh was reaffirmed in the 1980 case of Phang Chin Hock v. Public Prosecutor (as per www.wikipedia.org/Loh_Kooi_Choon_v._Government_of_Malaysia)

In summary, the Parliament cannot make radical changes to the Constitution. Especially regarding fundamental rights which are granted to individuals under the Constitution. Yes, equality under the law is a fundamental right

So what now? In order to properly implement hudud by way of legislation, the Parliament needs to come up with a new Federal Constitution because by reason of technicality they cant just amend the current one to suit hudud law. Ergo, hudud is NOT feasible with our current Federal Constitution

* This article can also be found at The Malaysian Insider