[en] This work explores the coupling of person-split nominative objects with anomalous subjects (Jahnsson’s Rule (JR), Person-Case Constraint (PCC)). In Breton, split-nominative objects spread from an Icelandic-like combination with oblique subjects of unaccusatives, to Finnish-like combinations with subjects of transitives in constructions like the imperative, and then retreated piecewise. These changes admit of externalist sources, such as frequency entrenchment and analogy over clitic forms, but are bounded by persistent coupling of split-nominative objects with anomalous subjects, and disfavour external sources for it like ambiguity avoidance. An approach is set out through constraints on φ-dependencies, their relationship to case and licensing, and their interaction with grammaticalisable partial φ-specification, building on other work on JR/PCC. The anomalies of the restricting subject are analysed as person-only specification, and extended from quirky obliques to pronouns minimal in absence of number + n/N : imperative pro and human impersonals. The ineffability or accusative of the restricted persons is analysed through the integration of dependent case into Φ/Case theory but apparent syntactic variation is modelled through externalisation.