This paper will examine the structure of the defendant-sided unjust factors, by which I mean duress and undue influence. The paper first argues that undue influence is based on abuse of deferential trust placed in the defendant and duress on an illegitimate threat leading to the claimant's lack of consent. The paper distinguishes undue influence from the unconscionable bargains doctrine. The paper then models the effect of that on the claimant's intentional agency by reference to Michael Bratman's influential theory of intention. It suggests that while mistake can be modelled by way of the failure of a condition on his intention, meaning that the claimant's intention does not cover the facts as they actually turn out to be, defendant-sided factors are based on the defendant's having improperly inveigled himself into the claimant's practical reasoning. It suggests that this happens either by way of the defendant's illegitimate structuring of the claimant's choice or by way of the claimant's deferring his judgment to that of the defendant. The claimant's intentions have, in philosophical language, agential authority, but the claimant was ‘in the grip of a norm’; the essay explores what this concept might be.