Pursuant to the Concordat between Italy and the Holy See, a canonical marriage has also civil effects, and so has a canonical judgment declaring such marriage null.
To obtain a judgement of this kind in the ecclesiastical forum is relatively easy, since you only need to prove that, at the moment of the marriage, you were not sincerely committed to the obligations that the Canon law lays down for the spouses: for example, that you were not willing to have children, or that you were willing to have only a given number of them.
There is the practical risk of a spouse applying for a canonical declaration of nullity in order to avoid to pay alimony, but until recently this was compensated by the fact that the canonical proceedings were long and expensive.
The Papal reform could now set off an avalanche of nullity proceedings. However, some judgments by the Italian Supreme Court have already limited the effects of the canonical declarations of nullity, deciding that they do not rule out the obligation to pay alimony.