In the Guaranty Trust Co. v. Commissioner of Internal Revenue case in 1937, the U.S Supreme Court was tasked with determining whether or not a trust's income could be taxed under federal law when that income had been assigned to another party by the beneficiary. The court ruled unanimously in favor of the Commissioner of Internal Revenue, stating that even if a beneficiary assigns their interest in a trust to another party, it does not change who is liable for paying taxes on its income. This decision established an important precedent regarding taxation and trusts: namely, that tax liability remains with whoever has legal title over property or funds rather than being transferred along with any benefits derived from them.

In the dissenting opinion for Guaranty Trust Co. v. Commissioner of Internal Revenue, Justice Cardozo disagreed with the majority's interpretation of tax law and its application to trusts. He argued that a trust should not be considered as an entity separate from its beneficiaries when it comes to taxation, but rather as a conduit through which income passes to them. In his view, this would mean that any income generated by assets held in trust should be taxed at the individual beneficiary level instead of being subject to double taxation - first at the trust level and then again when distributed to beneficiaries. This approach, he believed, was more consistent with both legal precedent and legislative intent behind relevant tax laws.