Yes, "libertarian" is probably not the right term - a quick skim of wikipedia shows that it is very broad with a varied attitude towards legitimacy of state power. What I specifically meant is that I don't see all restrictions on financial activity as a priori bad.

That said, why is the emphasis on constitution (BTW, do you mean any constitution or US constitution in particular)? Constitution is just a special kind of law after all and I can totally imagine libertarians claiming that it is inadequate, pushing to change it and make it more aligned with their principles.

I am specifically speaking about the USA as I am a libertarian from the USA, but the libertarian ideology is universal. It has a rich history of thinkers and writers if you want to explore more. Basically libertarians begin with the idea that the rights of the individual are the most important, and government should be restricted from infringing on individuals.

In the USA we have the Bill of Rights that protects each person from government overreach, such as the 1st amendment which protects freedom of speech, and the 5th amendment against testifying against yourself.

The government however often passes laws that violate these rights, and then the courts have to overturn laws that are unconstitutional because they violate our rights.

I am of the opinion that the government is a very dangerous entity with unlimited power and ability to harm citizens, so we should always be skeptical of all laws passed and work as much as possible to limit the power of government.