Can metalinguistic negotiations and 'conceptual ethics' rescue legal positivism?

In recent years, David Plunkett and Tim Sundell have published a series of interesting articles that made an original use of resources from linguistics and philosophy of language to reply to arguments for legal antipositivism, the thesis according to which moral or value facts are part of what determines what the law is in a given jurisdiction at a given time. Plunkett and Sundell’s strategy for resisting antipositivism appeals to the notion of a metalinguistic negotiation, which incorporates the notion of a metalinguistic or context disagreement. Sundell 2011 had argued that metalinguistic disagreements are a possible component of disputes about evaluative matters. A further notion deployed is that of conceptual ethics, an essential component of metalinguistic negotiations. This paper approaches a crucial concern about the deployment of both notions against disagreement-based arguments for legal antipositivism. Metalinguistic negotiations displace disagreements from the semantic to the metalinguistic level, but do not eliminate the appeal to moral or other normative reasons from legal disagreements. Conceptual ethics purports to be a normative activity, engaged with prescribing ways one ought to think and talk. On a broad understanding of legal reasoning and practice, metalinguistic negotiations and conceptual ethics are an integral part of it, and hence are consistent with evaluative and normative facts being essential to, and constitutive of, the law. Or so this paper argues.