A Cross-Appeal in Cassation May Raise Autonomous Claims

The criminal cassation appeal is the instrument by which the Spanish Supreme Court supervises the legality of judgments handed down by provincial courts and the National High Court. Within this channel, the figure of the cross-appeal — joining the opposing party's cassation appeal — has long raised a practically significant question: may the cross-appellant raise its own claims, or is it bound by what the main appellant asks for? A ruling of the Supreme Court of April 2026, issued in cassation appeal 6305/2023, answers clearly.

What a cross-appeal in cassation is

A cross-appeal is the procedural instrument that allows a party to join the cassation appeal brought by the opposing party, even though it did not appeal within the ordinary time limit. It is provided for in the Criminal Procedure Act (LECrim) and has been a common mechanism in criminal practice when a party that originally accepted the judgment decides, upon learning of the opposing side's appeal, that it has an interest in adding its own arguments.

The traditional view treated the cross-appeal as a subordinate position: the cross-appellant could participate in the proceedings, but its claims depended on those of the main appellant. If the main appeal failed, the cross-appeal fell with it. This restrictive reading left the defence with no room to raise autonomous issues before the Supreme Court if it had not appealed independently.

The Supreme Court's doctrine: cross-appeal with autonomous claims

The Supreme Court, in its ruling of 9 April 2026, recognises a broader scope for the cross-appeal. The Second Chamber accepts that a cross-appeal may function as an autonomous appeal, with its own claims and even claims contrary to those of the main appellant, in two clearly defined situations:

• First situation: where the cross-appeal introduces a new subject of challenge that benefits the accused. Here the accused who did not appeal may use the prosecution's appeal to raise favourable grounds before the Supreme Court that were not part of the main appeal.
• Second situation: where it is brought by a party that, without a grievance of its own, could be affected if the main appeal succeeds. This covers the case of a party that obtained a formally favourable ruling but would be harmed by the outcome of the opposing challenge.

In both situations the Chamber accepts that the cross-appellant is not chained to the main appellant's grounds or line of argument. The cross-appeal acquires, in these cases, its own procedural life.

Procedural framework: the LECrim channels

Criminal cassation is governed by Articles 847 to 901 of the LECrim. Grounds of cassation for a violation of law are brought under Article 849 — breach of a substantive criminal provision (849.1) or error in the assessment of evidence (849.2) — and grounds of procedural defect under Articles 850 and 851. The cross-appeal, as a vehicle for raising these same grounds autonomously, fits within this framework without creating a new channel, but rather widening the use of the existing one.

This configuration has an immediate practical consequence: a defence that chose not to appeal within the ordinary time limit — perhaps because the judgment was acceptable or the prospects of an independent appeal seemed poor — does not permanently close the door to cassation. If the prosecution appeals, the cross-appeal can become the vehicle for bringing defensive claims before the Supreme Court.

Limits of the autonomous cross-appeal

The doctrine does not turn the cross-appeal into an unconditional remedy. The limits are clear. First, the claims must connect with the subject-matter of the proceedings: the cross-appeal cannot be used to introduce issues unrelated to what was tried. Second, the formal framework of the cassation appeal remains the same: only the grounds listed in the LECrim are available, and the cross-appeal does not enable the factual review that ordinary cassation does not permit.

Third, the two situations the Chamber identifies require their specific conditions to be met: benefit to the accused or protection against the consequences of the opposing appeal. The cross-appeal cannot be used by the prosecution to extend its own claims beyond what it requested in its own appeal by joining the defence's cross-appeal.

Practical interest for the criminal defence

This doctrine is especially valuable in cases with mixed rulings, where the judgment contains both favourable and adverse pronouncements for the accused. If the prosecution appeals in cassation against acquittals or reduced sentences, a defence that had accepted the rest of the judgment may file a cross-appeal and raise its own claims before the Supreme Court — including grounds it could not have articulated in an independent appeal for lack of grievance on those points.

It is also relevant where the time limit for the defence's own appeal has lapsed and the defence, upon learning of the prosecution's appeal, identifies violations of law that would benefit the accused. The cross-appeal, understood as an autonomous remedy, restores in those cases a tool that the rigidity of cassation deadlines had apparently closed off.

Scope of the ruling and cassation framework

The April 2026 ruling fits within the ongoing consolidation of Supreme Court doctrine on the breadth of the criminal cassation appeal. The Court has been clarifying, in recent years, the contours of procedural figures whose regulation in the LECrim is sometimes sparse and has been supplemented by case law. The cross-appeal is one of them.

The ruling is relevant to any party to criminal proceedings that reaches the cassation stage without having appealed independently, but that, upon learning of the opposing party's appeal, identifies favourable grounds of its own. The doctrine opens the possibility of raising them autonomously, without being bound by the main appellant's claims or their procedural fate.