In Blair, Commissioner v. United States ex rel. Birkenstock et al., Executors, Etc., the Supreme Court ruled on a tax dispute involving estate taxes and life insurance policies. The executors of an estate argued that certain life insurance proceeds should not be included in the gross value of the decedent's estate for federal taxation purposes because they were exempt under state law. However, the IRS disagreed and assessed additional taxes based on these proceeds being part of the taxable estate. The case reached to Supreme Court which held that federal law governed what was includable in a decedent's gross estate for federal tax purposes, regardless of any exemptions provided by state law. Therefore, it upheld inclusion of all life insurance proceeds as part of taxable estates unless specifically excluded by provisions within Federal Tax Law itself.

In the dissenting opinion for Blair v. United States, Justice McReynolds disagreed with the majority's ruling that a grand jury witness could not refuse to answer questions on grounds of self-incrimination unless they were directly incriminating. He argued that this decision undermined the Fifth Amendment right against self-incrimination by forcing witnesses to guess whether their answers might be used against them in future prosecutions. He also expressed concern about potential abuse of power by prosecutors and grand juries, who could use this ruling to compel testimony from reluctant witnesses under threat of perjury charges. Furthermore, he believed it was unfair and unrealistic to expect ordinary citizens without legal training to understand which statements might incriminate them in hypothetical future cases.