The priest is the usual minister of Baptism, but if there is danger that someone will die without Baptism, anyone else may and should baptize.
Because Baptism is a necessary prerequisite to enter heaven, when an unbaptized person is in danger of death, and no priest is available, anyone may baptize. However, it would be very wrong to do it without serious reason.
In the early days of the Church, religious instruction preceded Baptism; the candidates for Baptism were called catechumens. In those days, solemn Baptism was administered on Holy Saturday, on the eve of Whitsunday, and on the eve of the Epiphany. From those early times has come our practice today of having the water for Baptism solemnly blessed on Solemn Easter Vigil, that is, on Holy Saturday night.
1. The bishop or pastor, or a priest properly delegated, is therefore the ordinary minister of Baptism. But in cases of necessity, when there is danger of death and an ordinary minister is unavailable, anyone–man, woman, or child, Catholic or non-Catholic, atheist, or pagan–may and should baptize; that person then becomes the extraordinary minister of Baptism.
When properly given, lay baptism is as valid as baptism given by a priest. In order to baptize validly, natural fresh water or holy water is poured, on the head, face, or body of the person being baptized, and at the same time the words are pronounced: “I baptize you in the name of the Father, and of the Son, and of the Holy Spirit.”
2. If a person baptized by an extraordinary minister survives, he cannot be baptized again. However, he is taken to the church, and the ceremonies that had been omitted are supplied.
No one may baptize himself. A witness to a lay baptism should be present, but this is not of necessity.
3. Baptism administered by a Protestant or other minister is valid if properly performed: that is, with the use of water, together with the form of Baptism, and having the intention to do what the Church does.
Conditional baptism is given when it is uncertain whether a person has been baptized, or when there is fear of the sacrament having been administered improperly.
4. Children should be baptized in the parochial church to which their parents belong, because the registration should be made there.
In case a child is baptized in a hospital, at home, or elsewhere, in some other church, the parish priest should be notified.
5. After Baptism, a certificate is given containing the names of the child, of his parents, of his godparents, the dates of birth, of Baptism, and the place of Baptism.
This is the BAPTISMAL CERTIFICATE. It should be very carefully kept, as later it will be needed for the sacrament of Confirmation. The certificate is also necessary for marriage, holy orders, or entrance into a religious community. Parents should tell their children when and where they were baptized, so that even should the certificate be lost and the parents die, the registration may be traced.