Legal realism [is] an approach that rose to prominence in the 1920s and lasted until the 1940s. Legal realism attacked two fundamental axioms of the traditional, formalist understanding of the common law: that common law legal rules were neutral and objective, and that the rules themselves could be determined with sufficient certainty. Realists maintained that all legal rules were indeterminate in the sense that any articulation of a rule was subject to multiple interpretations. As a consequence, when judges decided cases, they were not involved in an objective exercise of discovering the meaning of some preexisting rule or mechanistically applying a rule to a set of facts (because the indeterminate nature of legal rules conferred discretion on judges to choose from a variety of alternative interpretations), but rather the result would reflect the unstated public policy preferences of the judge. The inconsistent results in the contrasting cases of Re Drummond Wren and Re Noble and Wolf provide an example of the way in which a judge’s predisposition may affect legal out-comes. In essence, legal realism called into question the autonomy of law from broader social and political considerations.
"Legal Theory in Relation to Public Law," Craig Forcese et al in Public Law: Cases, Commentary and Analysis