This is always a difficult service to render. How do pastoral ministers judge readiness for acceptance? The rite does say it is the responsibility of the parish ministers. Let’s read:
43. Before the rite is celebrated, therefore, sufficient and necessary time, as required in each case, should be set aside to evaluate and, if necessary, to purify the candidates’ motives and dispositions. With the help of the sponsors (see RCIA no. 10), catechists, and deacons, parish priests (pastors) have the responsibility for judging the outward indications of such dispositions. (Ad Gentes 13) Because of the effect of baptism once validly received (see Christian Initiation, General Introduction, no. 4), it is the duty of parish priests (pastors) to see to it that no baptized person seeks for any reason whatever to be baptized a second time.
Two things of note. First, that parishes need to take an adequate period of time to assess their candidates for the catechumenate. Two, note the careful wording, that priests, with the help of deacons and lay people, can only judge outward indications. It is conceivable that a newcomer may be misjudged by a pastor or other people. Sponsors, obviously, become very important, having the personal contact with inquirers, as well as the experience of introducing them to prayer and the spiritual life.