Short answer. No. Article 167 is categorical: the child is legitimate even though the mother may have declared against its legitimacy, and even if she has been sentenced as an adulteress. Her admission is not something the law acts on, because legitimacy is a status belonging to the child rather than a claim she can give up.

What the law says

The child shall be considered legitimate although the mother may have declared against its legitimacy or may have been sentenced as an adulteress.

Family Code, Article 167 — Mother's Declaration Cannot Bastardize the Child. Read the full provision →

What the law says

Legitimacy of a child may be impugned only on the following grounds

Family Code, Article 166 — Grounds to Impugn Legitimacy. Read the full provision →

The status is the child's, not the mother's to surrender

The rule reads oddly at first, because in most areas of law an admission by a party is powerful evidence. Here it counts for nothing, and the reason is that the person whose interest is at stake is not the one speaking. Legitimacy attaches to the child. A mother cannot bargain it away, disclaim it in an affidavit, or destroy it by telling a registrar something different, any more than a stranger could. That is why the article is phrased as an instruction about the result — the child shall be considered legitimate — rather than as a rule about how much weight her statement carries.

Even a criminal conviction does not do it

The second half of the sentence goes further than most readers expect. The child stays legitimate even where the mother may have been sentenced as an adulteress. A conviction is a judicial finding after trial, and the Code still declines to let it settle the child's status. The point being made is about what the two proceedings are for. A finding about the mother's conduct answers a question about the mother. It does not answer the separate question of whether a particular child born in the marriage is the husband's, and the Code refuses to let the first stand in for the second.

Where the challenge has to come from instead

Article 167 does not make legitimacy unchallengeable; it channels the challenge. The Code sets out the grounds in Article 166, and that list is closed — legitimacy may be impugned only on the grounds stated there, which concern physical impossibility within a defined window before the birth, proof that biological or scientific reasons rule the husband out, and defects in consent to an artificial insemination. A mother's declaration is not among them. Nor is it a shortcut into them: her statement does not by itself establish that intercourse was impossible or that science excludes the husband, which is what the grounds actually require.

What this means in the registry, in practice

Most real disputes here start with paperwork rather than with litigation. A mother registers a birth naming someone else as the father, or signs an affidavit meant to reflect the family's actual situation, and years later a school, an embassy or an estate throws the discrepancy back at everyone. Article 167 means that document did not change the child's status; it created a record inconsistent with it. Correcting that is its own process, and it is not achieved by writing a fresh affidavit saying the opposite. Anyone in this position should have the marriage record, the birth certificate and every affidavit already signed looked at together before another one is executed.

Cases citing this provision

These Supreme Court decisions cite the provision above. We list them so you can read them yourself; the summaries of what each decided are not ours to give.

Related provisions

Note. Statute text quoted on this page is reproduced from the official enactment and is linked to the full provision. The explanation around it is general legal information from Vivas & Nobles Law Office, not legal advice. Whether it applies to your situation depends on facts only a lawyer reviewing them can assess.