In the case of Heiner v. Mellon, the Supreme Court ruled in favor of Andrew W. Mellon and his co-executors, overturning a decision by lower courts that had required them to pay additional estate taxes on gifts made within two years prior to death. The Internal Revenue Service (IRS) argued that these gifts were essentially part of the decedent's estate and thus subject to taxation under federal law at that time. However, the Supreme Court disagreed with this interpretation, stating it was not consistent with Congress' intent when they enacted relevant tax laws. The court held that for such transfers to be taxable as part of an estate under Section 302(c) of the Revenue Act 1926, there must be clear evidence showing transferor’s intention or expectation at time of transfer was imminent death which would cause inclusion in gross estate; mere possibility or even probability is insufficient proof without more direct evidence indicating specific motive behind gift transaction related directly towards impending demise rather than other personal reasons like generosity or family support etcetera.

In the dissenting opinion for Heiner v. Mellon, Justice Stone argued that the majority had misinterpreted both statutory language and legislative intent in their decision to allow a refund of estate taxes paid on an inheritance which was later returned due to legal challenges. He contended that Congress intended for such refunds only when property was physically or legally lost after being included in the gross estate, not simply because its value changed over time. Furthermore, he pointed out that allowing such refunds could create significant administrative burdens and potential inequities between taxpayers who were able to successfully challenge valuations and those who were not. Ultimately, Justice Stone believed this case represented a departure from established principles of tax law interpretation.