In Elfbrandt v. Russell, the Supreme Court, in a 5-to-4 decision, declared unconstitutional Arizona's requirement of a loyalty oath from state employees. At first glance, Elfbrandt appears to be just another decision voiding a state loyalty oath on limited grounds relating to the specific language of the particular oath. Yet, several aspects of Mr. Justice Douglas' opinion for the majority suggest that Elfbrandt is really of far greater significance: it may sharply limit the scope and coverage of loyalty oaths generally and, indeed, may presage a ruling invalidating all such oaths. Of course, only the Supreme Court can determine this. In the meantime, some evaluation by others seems appropriate, particularly in light of the numerous attacks against loyalty oaths currently being mounted in various state courts and legislatures.
Israel, Jerold H. "Elfbrandt v. Russell: The Demise of the Loyalty Oath." Sup. Ct. Rev. 1966 (1966): 192-252.