Secondary (delegated/subsidiary) legislation — rules, regulations, orders, by-laws, notifications made under statutory authority — is constitutional law's third layer. It raises three grave constitutional questions: Ultra vires: the delegation itself may be excessive, or the instrument may exceed the parent statute's limits — either way it is void. Rights invasion: delegated rules restricting expression, privacy or property invite fundamental-rights scrutiny (the reason "no prior censorship" type guarantees are read strictly against rule-makers). Competence trespass: in a federal scheme, a federal rule touching a Schedule-6 provincial or Schedule-8 local subject — or vice versa — produces federal-conflict litigation; Nepal's federal transition has been a workshop of exactly such disputes.
Other sub-statutory rules — parliamentary rules of procedure, standing orders, executive business-allocation rules — regulate the machinery the constitution creates and are binding within their sphere, but they cannot contradict statute, still less the constitution.