Passports: how old is too old?

Sean asks:

I know expired passports are okay, as long as they haven’t been cancelled but is there a time limit on that? This one expired in 2012

There are two ways a party can use a passport when they’re getting married: as proof of their date and place of birth, and as proof of their identity. So what are rules around expired and cancelled passports and the age of these documents?

Date and place of birth

A person’s date and place of birth will never change, so we can accept an expired passport that is 40, 60, 80 years old for this function. No problems how old it is. However…

Identity

What a person looks like changes dramatically throughout their life (as if I had to tell you that!) So for satisfying us as to their identity, the age of the passport matters very much. The current guidance (as per the Guidelines on the Marriage Act 1961 for Authorised Celebrants 2018, p52) is that:

An expired Australian passport that has not been expired for over 10 years can be used to determine the identity of a person [emphasis added].

However, the age of the passport is not the only deciding factor here. Sure, the passport might have been expired for less than 10 years, but it might also have been issued to the party when they were five years old; a child’s passport lasts for five years so it expired when they were 10, and they’re now 19 so it’s been expired for less than 10 years. But does the photo on the passport actually look like the person sitting in front of you? The Guidelines say in this regard:

An expired passport that belonged to a child may not be useful to determine the identity of an adult (even if it has been expired for less than ten years).

So yes, we can accept a passport that has been expired for up to 10 years, as long as the picture on it looks enough like the person sitting in front of us that it satisfies us as to their identity.

Clear as mud, right?