Collecting and producing documents held outside the country involves obligations that can conflict directly with a production order.
Data protection. Personal data in many jurisdictions may be processed and transferred only on a lawful basis, with transparency to data subjects, data minimisation and a valid transfer mechanism. Collection for litigation is possible, and it requires a documented assessment rather than an assumption.
Works councils and employee representatives must be consulted before monitoring or collecting employee data in several jurisdictions, and that process takes time.
Blocking statutes in a number of countries prohibit disclosure of certain information for use in foreign proceedings, with criminal penalties. Their practical enforcement varies, and courts asked to compel production weigh the importance of the documents, the specificity of the request, whether the information originated abroad, alternative means, and the interests of the foreign state.
Treaty routes for obtaining evidence are slow and are not exclusive, but using them first strengthens a comity argument.
Practical sequence. Map the data locations early; engage local counsel; use in-country review platforms where transfer is constrained; anonymise or filter before transfer where possible; and negotiate scope with the requesting authority, which is usually more productive than litigating comity.