Locative inversion in English (under the bridge lived a troll) is ungrammatical in all of the contexts where do-support applies: subject-auxiliary inversion, sentential negation, emphasis or verum focus, VP ellipsis, and VP displacement. Importantly, it is ungrammatical in these contexts whether do-support applies or not: it is ungrammatical with other auxiliaries, and it is also ungrammatical in nonfinite clauses of these types, where do-support never actually applies. This indicates that all of these contexts have something in common, and that cannot be disruption of adjacency between tense/agreement and the verb because there is no such disruption with other auxiliaries or in nonfinite contexts. These facts therefore argue against the standard last-resort theory of do-support, which holds that it is inserted to save a stranded tense/agreement affix, and for a theory like that of Baker 1991. In this theory, VPs have corresponding SPECIAL PURPOSE ([SP]) VPs, and do heads a [SP] VP. All of the contexts for do-support have in common the featural specification [SP]. Locative inversion involves a null expletive subject, the licensing of which is blocked by a non-[SP] context. All of this argues for a view of syntax with language-particular licensing constraints, features, and rules, within a range of variation proscribed by universal grammar.