Overview
- The Supreme Court Pleno voted 7–2 on June 4, 2026 in Amparo en Revisión 408/2025 to declare the IMSS rule that required five years of cohabitation unconstitutional.
- Justices struck the fixed five‑year cutoff but kept a requirement that claimants prove a real concubinage relationship using flexible, evidence‑based factors such as shared residence, financial ties, children and witness testimony.
- The ruling is binding nationwide and obliges the IMSS and lower courts to revise internal rules and to re‑evaluate past denials so affected people can file for review.
- Two dissenting ministers warned the change could create fiscal pressure and greater evidentiary uncertainty and argued that eligibility limits are a matter for Congress rather than the courts.
- The decision continues a recent SCJN trend expanding recognition of non‑marital families and stands in contrast to Spain’s Tribunal Supremo, which has held that long cohabitation without legal registration does not guarantee a widow’s pension.