Leggett and Garg predict that joint probability densities for the flux linking an rf SQUID in a coherent state will violate a set of inequalities analogous to Bell’s inequalities for a conventional EPR experiment. Observation of this effect would be a powerful demonstration of non-classical behavior in a macroscopic system. In this paper, a design for superconducting circuitry which are analogous to polarizers and particle detectors in a conventional EPR experiment are described for the rf SQUID. © 1990, Elsevier Science Publishers B.V. (North-Holland). All rights reserved.