Hugot gave us an overview of the vexillological considerations found in the constitutions of the world. His paper was entitled A Journey Through Constitutional Vexillology.
Interestingly many constitutions make no mention of the national flag. Often it is that older nations already have a prescribed flag, and it is over looked. However, younger nations often have clear descriptions of the flag, and a few even provide a graphic illustration.
Hugot pointed out that in the US, only in the first, now abandoned, constitution—The Articles of Confederation— mentions the US flag.