In Mississippi Choctaw, adjacent clausemate nouns cannot generally carry
identical case-markers (Broadwell 2006). I term this a 'Case OCP'
restriction, after similar phenomena in Hindi (Mohanan 1994) and Japanese
(Kuroda 1992, Hiraiwa 2010). Using data from original fieldwork, I show
that the Choctaw Case OCP is sensitive to a mixture of morphological and
syntactic factors: (a) the morphological form of the case suffix, (b)
linear adjacency, (c) the syntactic category to which the suffix is
attached, and (d) clause boundaries. Working within a Distributed
Morphology framework, I argue that Choctaw's Case OCP is active in the
morphological derivation at the point of Vocabulary Insertion (VI), but
must be able to 'see' category labels and hierarchical syntactic structure.
I further argue that it should be encoded as a violable constraint (or
rather, a pair of constraints), rather than as a filter on outputs.
