Havineinu, an abridged version of the daily prayer (Shemoneh Esreh), was once a useful, well known prayer said in pressing situations. Because it is brief, it is an ideal prayer for dangerous situations where one's ability to pray or concentrate on the longer text of the daily prayer is compromised. Yet, over the last several hundred years, the recitation of Havineinu has functionally ceased. This book addresses the legal analysis used to explain that change. This shift in perspective has been gradual, yet the resulting profound change in the interpretation of halachic texts has had a direct influence on the understanding and practice of Jewish law. This book examines the sources and processes that have shaped the contours of Havineinu over time, exemplifying the subtle changes that occur in the development of halacha as a result of chiddush -- innovation.