The United States Supreme Court has held that, if a defendant is given a preliminary hearing, it is a "critical stage" in a state's criminal prosecution in which the defendant is entitled to the aid of counsel and the appointment of counsel if necessary.
Coleman v. Alabama, 399 U.S. 1 (1970).
Criminal Procedure - Right to Counsel at Preliminary Hearing,
Duq. L. Rev.
Available at: https://dsc.duq.edu/dlr/vol9/iss3/15