Whether a person has a constitutional right to impugn a judgment procured by fraud and fraud on the court?

QUESTION PRESENTED | 1. Whether a person has a constitutional right to impugn a judgment procured by fraud and fraud on the court? 2. Whether state appellate court has a duty to vitiate a void judgment? 3. Does it violate the U.S. Constitution 14 Amendment due process when a state Supreme court affirms an appellate court’s decision that neglects to review issues presented on appeal regarding a void judgment? 4. Cana judgment procured ex parte constitute a valid judgment? 5. If attorneys negotiate, draft, forge a joint stipulation agreement without authorization on behalf of litigants and file it in the record of the court to procure a consent judgment constitutes a fraud and fraud on the court? 6. Whether it constitutes an unfair and impartial trial when a judge grants a motion to strike a subpoena of duces tecum requesting relevant and admissible information from the opposing party?