This class of causal inference methods relies on a restrictive class of admissible mechanisms $\mathcal{F}$ and focuses on identifiability results. The main idea is to show that in some cases there exist $f\in \mathcal{F}$ and $Q_N$ such that the hypothesis $\mathcal{B}_{\mathcal{G}, f, Q_N}$ holds in the causal direction $\mathcal{G}$ with respect to the observed data while there do not exist any $f' \in \mathcal{F}$ nor such $Q'_N$ that $\mathcal{B}_{\mathcal{G'}, f', Q'_N}$ holds in the opposite causal direction $\mathcal{G'}$.