A separation agreement is an agreement entered between couples on or during their separation, agreeing on terms for division of property, maintenance for support of a spouse and other financial arrangements such as trusts, company share transfers, etc.
Separation agreements are regarded in law as valid contracts as according to section 14 of the Matrimonial Property and Proceedings Ordinance. However, if any proceedings for divorce or judicial separation are issued subsequently, the existence of an agreement does not prevent the Court from making a different order. The reason was that any term in the agreement that restricts the right of any party to apply to the Court in future proceedings shall be void. The Court generally respects the concluded agreements and upholds them unless there is a compelling case of unforeseeable circumstances or having the contract enforced would impose injustice to either party.
When the parties have dispute on the existence of a valid separation agreement, or on the terms of agreement, the Court may rule on this point. For example, in WKK aka KKW v LMY aka MYL  HKCU 1021, the parties had dispute on whether the husband had promised to provide continuous maintenance to the wife until her remarriage. The Court found that the SMS messages between the parties were merely negotiations about the post-divorce arrangements and the husband’s previous financial provisions to the wife were done under guilt and pressure. The parties had never formed a binding agreement.