A constitutional republic is by definition a nation of laws. The question becomes if the government reflecting the wishes of the populous doesn't adhere to the constitution is it still a nation? Perhaps more importantly what is a nation?

The beauty of language is that it is a closed system for the most part. While definitions of words tend to change over time and new words are added, in the moment and with consideration of context, the definitions are more or less absolute. Some languages such as mathematics and logic because they are systems with many dependencies tend to stay constant and are very close to absolute. Spoken languages less so but remains a thinking tool. The important point is that all closed systems are abstract simplification of a incomprehensible complexity we call reality. While absolute in definition they are approximate in application. As a practical matter all we have is accuracy and precision not absolutes.

If we accept that the definition of a nation is a large body of people united by common descent, history, culture, or language, inhabiting a particular country or territory we can derive an approximate answer to the question is the US a nation. What is the tipping point where people are so disunited that a nation ceases to exist and may form multiple "nations" within a geographical boundary?

There is a general belief among liberals that the constitution is outdated. That the bill of rights needs to be expanded to include the right to an abortion, that freedom from gun violence is more important than the freedom to own guns, that some form of minimum income is a human right, so on an so forth. Liberal means free to not blindly conform to social traditions. The result ironically is anarchy enforced by liberal laws. Anarchy itself is a kind of prison. For example open borders and homelessness have made liberal sanctuary cities less free for their citizens. Crime, filth, diversion of funds to care for the freedom of illegal aliens and the homeless restrict the freedom of movement and services available to responsible citizens. The same principle applies to ignoring the constitution and the rule of law. The ensuing anarchy ultimately reduces the freedom of the responsible citizen. Freedom doesn't descend from anarchy but from responsibility. The responsibility to prevent unwanted pregnancies, the responsibility for self defense, the responsibility to contribute to society and support yourself, to keep anarchy and chaos at bay. To live a civilized life in cooperation with the other members of society.