A decision released on September 5, 2026, nr. 25009, by the Italian Supreme Court of Cassation ruled on an international inheritance involving an American citizen and real estate located in Italy.
In matters of succession upon death involving international elements, where the succession of a foreign national is governed—pursuant to Article 46 of Italian Law No. 218 of 1995—by the national law of the deceased, the Italian court must take account, under Article 13 of the same statute, of any renvoi made by the foreign conflict-of-laws rules, including a renvoi to Italian law. Furthermore, pursuant to Article 14, the court must ascertain ex officio the content of the applicable foreign law; the parties bear no burden of pleading or proving it.
Accordingly, where the relevant foreign legal system follows a system of **scission of succession**, distinguishing between movable assets governed by the law of the deceased’s domicile and immovable assets governed by the *lex rei sitae*, the court must assess the validity and effectiveness of the will separately in respect of each estate. The nullity of a consensual partition concerning assets that are not jointly owned remains unaffected, due to the absence of the typical causa of the partition agreement, where it is established that no hereditary co-ownership exists.
The dispute arose from the succession of a United States citizen who died in Pennsylvania. Several years after the opening of the succession, a will was discovered under which the deceased had appointed one of his children as sole universal heir. That child brought proceedings seeking recognition of his status as the sole heir, a declaration that the consensual partition previously entered into with his sister was null and void or ineffective, and restitution of the assets transferred pursuant to that agreement.
The defendant challenged the validity of the will, disputing the authenticity of the signature and alleging that the instrument failed to meet the formal and substantive requirements of Italian law. By way of counterclaim, she also sought recognition of her own status as an heir and, in the alternative, a reduction of testamentary dispositions allegedly infringing her reserved share.
The court of first instance recognized the claimant as the sole universal heir and declared the partition null and void. The Court of Appeal confirmed, insofar as relevant here, the validity of the will in light of United States law and the probate proceedings. However, it excluded the application of the *lex rei sitae* to the real property located in Italy on the ground that the parties had failed to plead and prove the content of the applicable foreign law.
The Italian Supreme Court of Cassation set aside that aspect of the appellate decision. It held that, under Law No. 218 of 1995, the court must ascertain ex officio the content of foreign law and determine whether that law makes a renvoi to Italian law, particularly in relation to immovable property located in Italy. The case was therefore remitted to the lower court for a determination of the succession rules applicable under Pennsylvania law and of the possible existence of separate estates.
The Cassation nevertheless confirmed the principle that a partition of assets that are not held in common is null for lack of causa, since the state of co-ownership is the functional prerequisite of a partition agreement.