Is baptizing someone without consent valid? (Roman Catholic view) Stemming from this question Is it valid to baptize multiple persons at once?, the question gives the scenario of one person baptising multiple people on a plane that is going to crash. The bit that confused me was towards the end when it says:


  and that air pressure has been lost leaving [the one doing the baptising] as the only one conscious


There is a comment as well:


  consent doesn't matter to the validity of baptism


According to the Roman Catholic church, if you baptise an adult who is not a believer and has not asked to be baptised (has not given consent), is that a valid baptism?
I think you'll find the section on Baptism in the Code of Canon Law helpful in answering your question.

Code of Canon Law: Title 1 - Baptism

To summarize a bit (please check out the link for the lion's share of details):


There is more than one way to be baptized, not all of which require a minister or other baptized person to be present. (e.g. the Baptism by Desire referenced by @Alypius above.) One form doesn't even require the recipient to be aware, but it's a special case (infants) that assumes the guardians have the infant's best interests at heart.
Consent is mandatory, and the person must be alive. This is where Catholic baptism parts ways from Mormon baptism. In the latter, it is acceptable to baptize the dead.


So, if the people on the plane expressed a desire to be baptized, and gave their consent, it matters little that they're conscious or not when the sacrament is conferred. An infant isn't cognizant of the act, yet it is acceptable to baptize the infant (for many reasons that you'll find in "illuminated" versions of the Code of Canon Law.)

Here's another pretty decent source of info (goes into much greater detail than the Code of Canon Law): Catholic Encyclopedia