Carrying out the entire judicial investigation on appeal would limit the jurisdiction of the stakeholders and thus affect their right to a full defense.

Just another way of expressing or 'piggy-backing' the idea, though I - with minimal Romanian language skills - can't make out if this is a civil or criminal scene - investigation (E&W: examining justices' committal) stage suggests the latter.

Obiter, a translational strategy, ploy or trick is to use jurisdictional as an adjective, so an 'exception' or 'objection to the court's jurisdiction' becomes a straight 'jurisdictional plea' (aka plea (as) to the jurisdiction).

'Conducting the entire judicial investigation on appeal would rob the parties of one / a jurisdictional tier and interfere with / encroach upon their right of defenc/se.'