Mom is a practicing Catholic; father is not a Catholic; mom and dad are not married (to each other or to anyone else). The father is a meth addict. Mom went to her local church and was advised that the father must be present at the baptism or give written permission for the baptism to take place. Is this correct?
The Code of Canon Law states:
For an infant to be baptized lawfully it is required: that the parents, or at least one of them, or the person who lawfully holds their place, give their consent (canon 868 §1 1°, emphasis added).
Under ordinary circumstances, as a matter of prudence, parishes reasonably try to ensure that both parents consent to the baptism. But if the Catholic mother has sole custody and the non-Catholic father is incapable of consent due to his addiction, it would seem to me that an exception can be made at the discretion of the baptismal presider, in accord with canon law.