That just means that they have to follow the rules. It doesn't mean that it has to be fair. The prisons are full of people who got due process but they didn't a fair trial or justice for that matter.
So, if you have issues with how the laws are made in this country, that's different from the foundation of this country.
But don't talk about justice. We have a legal system, not a justice system. There can be no justice until G-d restores the earth. We should do justice and do our best - but even that requires that everyone involved in our justice system also love righteousness and walk humbly before G-d. I don't see that happening any time soon.
Shalom.