How can a state claim Sovereign Immunity to prevent a citizen of that state to sue them when Due Process is guaranteed to individual citizens by the 14th Amendment?

Answer 1

A complete answer to this question would require volumes. In brief, very brief fashion, due process means that government action, meaning state, federal, and local governments and their agencies must not deprive any citizen of any fundamental rights without a fair hearing. It gives the federal government the power to make states give its citizens the rights guaranteed under the federal consitution. Sovereign Immunity, in very brief fashion, means that a state, as a state, cannot be sued without its permission. In reality sovereign immunity almost never has any application. States do not use sovereign immunity in personal injury cases. They allow such suits. Also, almost any suit you can think of can be brought against a department of the state, such as state highway commissions, cities, counties, etc. These are not covered by immunity. Brown v. Board of Education which integrated school systems is such a case.