If two Americans got married on a cruise ship in Mexico is their marriage legally binding in the US?

Short

If the marriage is legal in Mexico, it will be legal in the US.

Detailed

The following are the requirements for marriage in the Federal District (Mexico City). However, marriage requirements prevailing in the thirty-one states of Mexico are in general very similar to those of the Federal District.

1. An American or other foreigner wishing to be married in Mexico must present to the appropriate Civil Registry certain documents described in the paragraphs below. All documents from the U.S., except for the valid U.S. passport, must be authenticated by an American authority (usually the Secretary of State), from the state where they originated, who attaches an "Apostille" to the document.

2. In Mexico, only civil marriage is recognized as legal. Persons wishing to do so may also have a religious ceremony, but it has no legal effect and does not replace in any way the legal binding civil marriage. A civil wedding in Mexico is fully valid for legal purpose in the U.S.

3. Civil marriages are performed by the Civil Registry of each municipality (Registro Civil). The address of the main office of Mexico City's Civil Registry is:

Oficina del Registro Civil Arcos de Belen y Doctor Andrade 06720 Mexico, D.F. tel. (011-52-5) 578-7140

4. Marriages are performed without charge at the premises of the "Registro Civil". They may also be performed elsewhere, but in this case a fee is charged which should be ascertained from the "Registro Civil".

5. Persons desiring to marry must fill out at an application at the corresponding office of the "Registro Civil", which will include a statement as to whether they wish to marry under the system of joint or separate marital property. This application will have to be accompanied by a certificate from a physician in Mexico that they are free of those diseases which are impediments to marriage (a blood test and X-rays taken in Mexico are required).

6. Foreigners are not subject to a residence requirement but will have to identify themselves by a presentation of their tourist cards and of a valid passport and a copy of their birth certificates authenticated and translated as described in paragraph 1 above. Foreigners planning to marry a Mexican citizen should pay particular attention to the special requirements listed in paragraph 9 below.

7. Persons previously married must present proof of the termination of that marriage in the form of a divorce decree or death certificate. If the divorce or death took place outside of Mexico, it must be authenticated and translated in accordance with the information given in paragraph 1 above. Divorced people cannot marry in Mexico until one year after the termination of the divorce.

8. Persons under the age of eighteen cannot be married without the consent of their parents or legal guardians. If the parents or guardians cannot be present at the marriage, they must grant a power of attorney to another individual to exercise the parental consent at the ceremony. This power of attorney must be authenticated and translated in accordance with the instructions given in paragraph 1 above.

In sum, the marriage has to be legally reconized in Mx before it will be recognized in the US.