Lacan’s approach to the function of law, as understood in such a way that might be relatively easily bifurcated into the (predominantly) implicit – incest prohibition – and functionally explicit – the ten commandments – is presented in relation to the reality principle: the seemingly necessary repression of the id with, or in, the aim of optimising the subject’s ability to function in accordance with the demands of society.
Unsurprisingly, Lacan indicates the Oedipal relation – desire for the Mother, rebuffed by the nom / non of the Father – as the birth of the reality principle, and accordingly presents the fundamental “demand” of society within the parameters of a negative imperative. The instigation of this economy of disavowal is the introduction of (to?) the Symbolic order, consequently and crucially speech itself and, in such an introduction, demarcates the un/representable. The un-sayable, within a linguistic structure so fundamentally reliant upon (e.g RE: the ten commandments) the saying of “no.”)
It is for such a reason that Lacan states the ten commandments do not explicitly ban incest: the incest prohibition as the sine qua non of speech itself, is seemingly implicit in the commandments, simply for their ability to be said at all. Accordingly, the explicit negatives in the commandments operate as secondary repressions of that primary repression: the listed crimes might be understood as figures in a masquerade of tension between the subject and the primary, problematically (certainly oxymoronically) indicating and alienating.
It is this troublesome masquerade that parallels Derrida’s account of the supplement: the Mother is rendered the Thing, which is represented through various nominally rejected means. Such a process of representation and repression feels indicative of the supplementary failure of the signifying function of speech: always in absence or excess of its referent of desire.
Thus, this problematic chain of signification embodied in the cultural/legal process of supplementary disavowal speaks to the problem of repression, as that which makes us aware, without being conscious, operating as the natural inverted reflection of perversion’s desire to represent that which seemingly cannot be successfully, wholly, transmitted.