The Church has an extensive process for choosing new bishops
Although the appointment of a bishop usually involves a great deal of contributions from other existing bishops, it is ultimately a decision made by the sole discretion of the Pope.
“The process for selecting candidates for the episcopacy normally begins at the diocesan level and works its way through a series of consultations until it reaches Rome,” says the United States Conference of Catholic Bishops. “It is a process bound by strict confidentiality and involves a number of important players – the most influential being the Apostolic Nuncio, the Congregation for Bishops, and the Pope. It can be a time-consuming process, often taking eight months or more to complete. While there are distinctions between the first appointment of a priest as a bishop and a bishop's later transfer to another diocese or his promotion to archbishop, the basic outlines of the process remain the same.”
In the first stage of the process, the bishops of a given province (an area which includes an archdiocese and one or more dioceses) meet after having submitted to their archbishop their recommendations of priests they consider good candidates for the episcopacy (every candidate must be at least 35 years old, be a priest ordained for at least five years, and “hold a doctorate or at least a licentiate in sacred Scripture, theology or canon law, from an institute of higher studies approved by the Apostolic See, or at least be well versed in these disciplines,” according to the Code of Canon Law, 378 §1-5).
This meeting of the bishops concludes with a vote; the vote tally and the meeting minutes are then sent to the country’s appointed Apostolic Nuncio (the Vatican’s diplomatic representative before a foreign state) and to the local episcopal conference.
In the second stage, the Apostolic Nuncio puts together a detailed file on each candidate, which includes consultation of previous bishops of the diocese, current bishops of the province, the President and Vice President of the USCCB, and many people who know the candidates personally. He concludes this stage by sending a list of three candidates, called a terna, with all his findings and his recommendation from among the three to the Congregation of Bishops.
In the third stage, this Congregation reviews and discusses the terna. The Congregation gives great weight to the Nuncio’s recommendation but is free to choose another of the candidates or to ask that another terna be prepared.
In the fourth stage, the prefect of the Congregation for Bishops gives the Pope the recommendation of the Congregation; the Pope then presents his decision to the Congregation within a few days. The decision is related to the Nuncio, who puts it before the candidate for his acceptance or rejection. Upon the candidate’s acceptance, the information is sent back up the chain to the Vatican, and a date is set to announce the appointment. The candidate must then be consecrated as a bishop within three months of receiving the Pope’s appointment.