The aim of this paper is to provide a comprehensive account of the characteristics of Spanish CLLD. Specifically, I discuss two things. Firstly, I focus on identifying the nature of the resumptive pronoun. Secondly, I try to account for why CLLD exhibits typical and non-typical properties of A'-movement at the same time. For the first goal, I compare the resumptive pronoun appearing in relative clauses with the one appearing in CLLD. Based on the fact that they are very different in some respects, I suggest that they are different in nature: the resumptive pronoun in relative clauses is a PF-gap filler, whereas the resumptive pronoun in CLLD is a determiner. For the second goal, I present a new structure for CLLD which includes the movement of a null operator to [Spec,CP]. I demonstrate that this structure enables us to account for the dual properties of CLLD. Based on the fact that a null operator behaves on a par with an overt operator with respect to syntactic island effects, but it behaves differently from an overt operator with respect to subject-verb inversion, multiple appearances in [Spec,CP], the WCO effect and the licensing of parasitic gaps, I argue that the two conflicting properties shown by CLLD are closely related to the movement of the null operator. In other words, it is the two opposing aspects of the null operator that cause both the typical properties of A'-movement and the non-typical properties of A'-movement.