Under the Civil and Commercial Code (CCC), Book V, Sections 1546-1555, paternity is determined by:
(a) The birth mother, who is automatically the legal mother (Section 1546).
(b) The husband of the mother at conception or birth is presumed the legal father (Section 1547). Paternity outside marriage requires acknowledgment or judicial proof (Section 1555).
The Protection for Children Born through Assisted Reproductive Technologies Act (B.E. 2558, 2015), Section 21, assigns paternity to the intended parents in regulated ART, excluding clinical donors. Informal donors are not covered and risk paternity if proven outside this framework.
Assisted Reproduction:
Thailand regulates ART under the 2015 Act (B.E. 2558), permitting sperm donation in licensed facilities for married heterosexual couples only. Informal sperm donation is not recognized and is effectively prohibited outside this framework.
Donors lack legal protections against paternity claims if biological ties are proven outside regulated ART. Single women and same-sex couples are barred from ART (Section 5); informal donation is rare due to legal and cultural barriers.
Sperm Donor Agreements:
Clinical donors are protected from paternity under the 2015 Act (Section 21), but informal agreements lack a legal framework. Contracts outside regulated ART are unenforceable under the CCC, and donors risk paternity if acknowledged or proven (Section 1555).
For NI or informal AI, the donor could be deemed the legal father if paternity is established judicially, lacking statutory protection.
Surrogacy:
Altruistic surrogacy is permitted under the 2015 Act (Sections 23-27) for married couples, with intended parents recognized as legal parents. Commercial surrogacy is banned (Section 6). Informal surrogacy defaults to the birth mother as legal mother (Section 1546).
International surrogacy arrangements require legal proceedings for recognition.
Parentage Agreements:
Parentage is formalized through marriage, ART regulations, or birth registration (CCC Sections 1546-1555). Informal agreements lack enforceability unless judicially recognized (Section 1555).
Courts may establish paternity based on biology or acknowledgment, overriding informal agreements if disputes arise.