I haven't posted in what seems like years, but as one who was formed in a Roman Catholic Seminary and then later ordained an Episcopal priest, I think that the systems are similar enough for comparison.  From start to finish the discernment process is a journey at the parish and diocesan level with the candidate and both lay and ordained people who consult the bishop.  When the candidate is admitted to postulancy they begin formal theological which ends in their ordination.  The Bishop cannot ordain on his/her own whim, it must be with the consent of the ordained and lay members of the Diocese.  The same as to Episcopal Elections. Both lay and ordained must elect the Bishop and then the each Bishop and Diocesan Standing Committee must consent before the person in ordained a bishop. The Presiding Bishop is elected from the House of Bishops.  As with all systems sometimes it works well and other times, not so...but it is a system that trust the Spirit to speak through everyone involved.