[Dr. Eckleburg]

petition of nullity from one or both spouses.

One or both??? So if one spouse wants an annulment, that's valid grounds for it?

This is a more liberal reading than even I thought.

Another one of the flexible inflexibles.

[annalex]

if one spouse wants an annulment, that's valid grounds for it?

That satisfies one condition of several. There must be a petition that challenges the validity of the marriage and it has to come from one of the spouses. After that is satisfied, the canon law will look into the substance matter, chiefly dealing with informed consent and ability to marry.