The unknown, precisely because it is unknown, causes suspicion and fear. What does the lawyer feel when he faces an unknown legal institution? How does the translator react in such a case? In this article we study both the reaction of the Spanish legal community and also that of translators in Spain when facing an unknown legal institution like the trust. That enables us to realise that there is a close relationship between the attitude of the legal translator when faced with a new institution like the trust and the view taken by international private law rules as well as that of the legal community in charge of applying foreign law. Furthermore, we compare the attitude of the Spanish translators and the legal community in Spain, rather conservative, with that of other countries, like Canada, which have shown to be more open minded. Finally, we put forward translation strategies based on the calque and loan of the foreign word.