54It should be noted that it is not a matter, for the institution, of imposing its view or of substituting its own assessment for that of the Member State concerned, but of preventing the adoption of a decision which it does not consider to be defensible. The institution, as author of the decision granting or refusing access, is responsible for the lawfulness of that decision. In consequence, before refusing access to a document originating from a Member State, it must examine whether the latter has based its objection on the substantive exceptions provided for in Article 4(1), (2) and (3) of Regulation No 1049/2001 and whether it has provided a proper statement of reasons with regard to those exceptions (see, to that effect, Sweden v Commission, paragraph 6 above, paragraph 99).