There are NO LAWS requiring States to demand its citizens to carry a nationality card for identification of their nationality.  States know the nationality of its citizens, it is the one that confers it.

 

Nationality law is the law in each country and in each jurisdiction within each country which defines the rights and obligations of citizenship within the jurisdiction and the manner in which citizenship is acquired as well as how citizenship may be lost.

 

A person who is not a citizen of the country is generally regarded as a foreigner, also referred to as an alien.

A person who has no recognised nationality or citizenship is regarded as stateless. By international custom, each sovereign state has the right to determine who it will recognise as its nationals and citizens. Such determinations may be made by custom, statutory law, or case law (precedent), or some combination. In some cases, the determination may be governed by public international law.