When a Sister’s Promise Becomes a Legal Contract: Mills v Dodds

Sometimes the most heartfelt promises, especially from loved ones facing their final days, can echo beyond the grave.

In a rare but powerful testament to the enforceability of heartfelt commitments, the Supreme Court of New South Wales in Mills v Dodds [2025] NSWSC 396 has reaffirmed that a promise, made even in life’s most emotional moments, can carry binding legal weight if properly supported under contract law.

The Story in Brief

• The Promise: Jennine Mills moved from Victoria to NSW and cared for her terminally ill sister, Lynette, for about 10 months, after Lynette allegedly promised her by phone, “If I promise you half of my estate when I die, would you come up here and look after me?”
• No Will to Reflect the Promise: Lynette never updated her Last Will, instead appointing a friend as executor and leaving only a modest amount to Jennine.
• The Legal Battle: Jennine then commenced proceedings claiming:
  • a testamentary contract – there was an enforceable contract between herself and Lynette; or alternatively,
  • an equitable estoppel claim – that equity should intervene to enforce the promise based on estoppelo.

 
The executor counterclaimed, seeking about $80,000 in withdrawals Jennine made shortly before Lynette’s passing.

As of 8 December 2023, Lynette’s residuary estate had been calculated to total just over $1.05 million.

Issue

The Court was required to determine whether there was an enforceable contract that existed between the two sisters, Jennine and Lynette.

The Court’s Ruling: Contract Wins the Day

Justice Meek acknowledged at [420] that “a testamentary promise is enforceable (or otherwise) according to ordinary contractual principles and, if a claimant is successful in his or her contention, as promise, he or she receives under the contract a right to an effectual transfer of the relevant asset under the promisor’s Will.”

Justice Meek’s decision is carefully rooted in established contract principles under NSW common law:

1. 1. Agreement Exists: The Court determined that the promise was unequivocal and made under serious circumstances.
   2. Certainty of Terms: “Half of my estate” was a sufficiently clear promise for legal enforcement.
   3. Consideration Provided: Jennine’s move interstate, quarantine, and full-time caregiving for 10 months were deemed real and legally adequate consideration.
   4. Intent to Create Legal Relations: The context of terminal illness and the gravity of the request pointed to a serious and enforceable promise.

Result: Essentially, Lynette’s failure to update her Will was a breach of contract.  Jennine was awarded damages equivalent to half of the residuary estate.

Additionally, the court found that the cash withdrawals Jennine made were authorised by the deceased and not recoverable by the estate.

Alternative Argument Left on the Bench

Justice Meek did not decide on the estoppel claim because contract law provided a clear and sufficient remedy.  No need arose to determine whether an equitable remedy might also apply.

Broader Implications for Estate Planning

This case signals critical reminders for estates and family law planning:

• Verbal Promises Can Be Binding: Especially when paired with valid consideration, even oral promises can override testamentary freedom.
• Document Everything: Estate plans must reflect current intentions; codicils or updated wills are essential when circumstances or promises change.
• Caregiving Is Consideration: Acts of care, especially under emotionally significant circumstances, may constitute legally sufficient consideration.
• Equitable Claims Stand Back: Contractual principles may suffice, simplifying disputes vs. relying on discretionary equitable remedies.