Supplemental Relative Clauses and Syntactic Generality

0. Introduction It is generally assumed in research on non-restrictive relative structures (Ross 1984, Espinal 1991, Potts 2002a, Arnold 2007) that sentences like those in (1) are ungrammatical due to a general constraint of the form “nonrestrictive relative clauses must ... follow their antecedents” (Espinal 1991:752). The presence of such a linearization constraint seems reasonable enough given the fact that restrictive relative clauses also cannot left-adjoin (*a who I met child).