This is one for the conflict of laws anoraks. In C-29/16 HanseYachts the Court of Justice held (on 4 May) that an application for proceedings to preserve or establish, prior to any legal proceedings, evidence of facts on which a subsequent action could be based, does not constitute a proceeding within the meaning of (now) Article 32(1) Brussels I. If it had, it would trigger the lis alibi pendens regime of that Article, impacting therefore on any future substantive proceedings.
At 33 the Court defers to the insight into the relevant provisions of French judicial procedure, offered by the French Government: Although there may indeed be a connection between the court seised on the basis of the relevant French Article and the court having jurisdiction to hear the substance of the case with a view to which the measure of inquiry was ordered, the fact remains that such proceedings for the taking of evidence are independent in relation to the substantive procedure which may, if necessary, be brought subsequently. The Court’s ruling however is dependent (at 34) upon the French courts confirming this interpretation of French civil procedure: for the CJEU does not offer final interpretations on internal State law.
Of note is of course also that the Court seized with the substantive procedure, may en parcours de route take measures to preserve evidence etc.: that court would have already been ‘seized’.
(Handbook of) EU Private International Law, 2nd ed. 2016, Chapter 2, Heading 220.127.116.11.