If the parties to an agreement governed by Cayman Islands law would like the agreement to take effect from a date earlier than the date upon which the agreement was signed and entered into, the parties should expressly state in the document that it is intended to be effective from a date earlier than the date on which the parties entered into the agreement. It should be made clear in the document that notwithstanding it being entered into on the date of execution by the parties, it is to take effect from a date in the past.
Stating that the contract or agreement will be effective from an earlier "effective date" will, however, only be effective as between or among the parties to the contract or agreement. It will not affect those parties' obligations under the terms of the contract or agreement with regard to third parties who are not parties to the agreement. The obligations to third parties will almost invariably be based on the date that the contract or agreement was fully executed subject to any applicable special circumstances.
It is worth noting that whilst parties signing a contract or agreement may expressly state that the contract or agreement is effective from a date in the past, the parties should not "back-date" the date of execution (for example, sign the contract or agreement today and but insert an earlier date as the date of the document, thereby making it seem as if it was signed on some earlier date). This could run the risk of civil and/or criminal sanctions in a number of jurisdictions (for example, depending on, among other things, the nature and subject matter of the contract or agreement, false accounting or false statements by directors, or even conspiracy to defraud).