Why do courts always apply their own procedural rules?

In the context of conflict of laws, it is a standard principle that a court will always apply its own procedural law, known as the lex fori.1

This practice is rooted in the fundamental nature of procedural law, which governs the machinery of the courts and the methods by which rights are enforced. Because procedural rules are designed to ensure the efficient, systematic, and formal operation of a specific judicial system, they are inextricably linked to the court's own administrative framework. Applying foreign procedural rules would be impractical, as it would require a court to operate using methods, evidence rules, and management structures that differ from its own established civil procedure.2

While courts generally apply their own procedural rules, there is no universal agreement on the distinction between procedural and substantive issues. For example, statutes of limitations are classified as substantive in some legal systems and procedural in others, which can lead to varying applications of the lex fori.1