This book is based on a doctoral thesis submitted to Yale University Law School in 1968. I wish to acknowledge my deepest gratitude to my super­ visor in the writing of the thesis, Professor Ronald M. Dworkin, whose in­ sights and criticism have conspicuously contributed to the present work. Time and again I have been inspired by the ideas expressed by hirn both in personal discussions and in his Conflict of Laws and Jurisprudence courses. It has been my privilege also to have had Professors Leon S. Lipson and Guido Calabresi as supervisors. I have derived great benefit from their sug­ gestions. A sincerely feIt appreciation is expressed to all three persons. A special debt of gratitude is owing to the Yale Law School for the gener­ ous financial support extended to me. I also wish to record my indebtedness to the Hebrew University of Jerusalem and to Tel-Aviv University for their financial assistance. I am extremely grateful to Mr. Michael Reiss, '68 Yale Law School for his significant editorial assistance. Thanks are also due to my wife Ettie for invaluable help and encouragement. Finally, I wish to thank the publishers for their courtesy and cooperation. A.S.