What is an authoritative order that has the force of law?

An authoritative order that has the force of law is best described as a decree. A decree is a formal and official order issued by a person or body in authority, often used in governmental and legal contexts to establish rules or direct actions. It carries legal weight and must be adhered to, similar to a law. This is why, in contexts such as judicial procedures or executive governance, a decree can have significant implications and enforceable authority.

On the other hand, the other terms do not fit this definition. A deluge typically refers to a severe flood or overwhelming influx, not a legal term. Decimate means to destroy a large proportion of something, most commonly used in a general sense rather than a legal context. Defiance refers to an act of resistance or bold disobedience against authority, which does not convey the sense of an official order or legal mandate. This contextual understanding reinforces why a decree is the appropriate choice in this scenario.