From the Code of Canon Law;
THOSE TO BE BAPTIZED
Can. 864 Every person not yet baptized and only such a person is capable of baptism.
Can. 865 §1. For an adult to be baptized, the person must have manifested the intention to receive baptism, have been instructed sufficiently about the truths of the faith and Christian obligations, and have been tested in the Christian life through the catechumenate. The adult is also to be urged to have sorrow for personal sins.
§2. An adult in danger of death can be baptized if, having some knowledge of the principal truths of the faith, the person has manifested in any way at all the intention to receive baptism and promises to observe the commandments of the Christian religion.
Can. 866 Unless there is a grave reason to the contrary, an adult who is baptized is to be confirmed immediately after baptism and is to participate in the eucharistic celebration also by receiving communion
Can. 867 §1. Parents are obliged to take care that infants are baptized in the first few weeks; as soon as possible after the birth or even before it, they are to go to the pastor to request the sacrament for their child and to be prepared properly for it.
§2. An infant in danger of death is to be baptized without delay.
Can. 868 §1. For an infant to be baptized licitly:
1/ the parents or at least one of them or the person who legitimately takes their place must consent;
2/ there must be a founded hope that the infant will be brought up in the Catholic religion; if such hope is altogether lacking, the baptism is to be delayed according to the prescripts of particular law after the parents have been advised about the reason.
§2. An infant of Catholic parents or even of non-Catholic parents is baptized licitly in danger of death even against the will of the parents.
Can. 869 §1. If there is a doubt whether a person has been baptized or whether baptism was conferred validly and the doubt remains after a serious investigation, baptism is to be conferred conditionally.
§2. Those baptized in a non-Catholic ecclesial community must not be baptized conditionally unless, after an examination of the matter and the form of the words used in the conferral of baptism and a consideration of the intention of the baptized adult and the minister of the baptism, a serious reason exists to doubt the validity of the baptism.
§3. If in the cases mentioned in §§1 and 2 the conferral or validity of the baptism remains doubtful, baptism is not to be conferred until after the doctrine of the sacrament of baptism is explained to the person to be baptized, if an adult, and the reasons of the doubtful validity of the baptism are explained to the person or, in the case of an infant, to the parents.
Can. 870 An abandoned infant or a foundling is to be baptized unless after diligent investigation the baptism of the infant is established.
Can. 871 If aborted fetuses are alive, they are to be baptized insofar as possible.http://www.vatican.va/archive/ENG1104/__P2X.HTM