In the paper we argue that truth-relativism is potentially hostage to a problem of exhibiting witnesses of its own truth. The problem for the relativist stems from acceptance of a trumping principle according to which there is a dependency between ascriptions of truth of an utterance and ascriptions of truth to other ascriptions of truth of that utterance. We argue that such a dependency indeed holds in the case of future contingents and the case of epistemic modals and that, consequently, the relativist about these domains cannot exhibit witnesses to his relativism. In the appendix we provide some results on the relation between trumping and multi-order relativism.