This judgment clarifies that under Order XI Rule 1(10) CPC, as applicable to commercial suits, “reasonable cause” for non-disclosure of documents with the written statement demands a genuine, specific explanation, with a lower proof threshold than “good cause” but mandating demonstration that documents were not in the defendant’s power, possession, custody, or control at filing; mere delay or post-appeal discovery without prior diligence does not suffice, reinforcing the Commercial Courts Act’s intent for vigilant, time-bound litigation over procedural leniency in ordinary suits.