A question which should never have needed to be asked...

answered authoritatively by the CDF:

CONGREGATION FOR THE DOCTRINE OF THE FAITH
RESPONSES TO QUESTIONS PROPOSED
on the validity of Baptism conferred with the formulas
«I baptize you in the name of the Creator, and of the Redeemer, and of the Sanctifier»
and «I baptize you in the name of the Creator, and of the Liberator, and of the Sustainer»

QUESTIONS

First question: Whether the Baptism conferred with the formulas «I baptize you in the name of the Creator, and of the Redeemer, and of the Sanctifier» and «I baptize you in the name of the Creator, and of the Liberator, and of the Sustainer» is valid?

Second question: Whether the persons baptized with those formulas have to be baptized in forma absoluta?

RESPONSES

To the first question: Negative.

To the second question: Affirmative.

The Supreme Pontiff Benedict XVI, at the Audience granted to the undersigned Cardinal Prefect of the Congregation for the Doctrine of the Faith, approved these Responses, adopted in the Ordinary Session of the Congregation, and ordered their publication.

Rome, from the Offices of the Congregation for the Doctrine of the Faith, February 1, 2008.

William Cardinal Levada
Prefect

+ Angelo Amato, S.D.B.
Titular Archbishop of Sila
Secretary

By the way, note that the question seems to originate from the English-speaking world. In the Latin original and all the translations, the defective formulae are given in English.