How does a government go about creating Legality?

by creating and then voting to pass new lawsHow does a government go about creating Legality?
Who says they even bother most of the laws passed are not legal or constitutional as it is, They extend there own terms in office give themselves giant raises and if they commit a crime leave and get another position in a different department and nothing is done about there crimes.How does a government go about creating Legality?
They have a section named a Congress and they have to pass a bill in order for a legal action to take place. It is voted on and the bill with the less votes is the legal action that won't be taken unless more votes are acquired by Congress.