What is due process? what might happen if the constitution did not guarantee this right?

list the three main categories of rights that citizens enjoy.

i doesn't matter if you answer both, or only one, but !

give short and simple answers asap : )

The three main categories of rights that citizens enjoy are 1) the right to be protected from unfair actions of government, 2) to have equal treatment under the law, and 3) to have basic freedoms. 

Due process is a right to fair treatment in the judicial system, and if the Constitution didn't guarantee this right, it probably wouldn't have lasted very long.