What is the test for warrantless entry into a house by a police officer?

Courts have recognized the combustible nature of domestic disputes, and have accorded great latitude to an officer's belief that warrantless entry was justified by exigent circumstances when the officer had substantial reason to believe that one of the parties to the dispute was in danger. For example, in Magnuson v. Cassarella, 813 F.Supp. 1321 (N.D.Ill.1992), police were called to the scene of a domestic disturbance by a neighbor who heard screams and was concerned about the infant in the house. Id. at 1322. When the police arrived outside the house, the neighbor reported--and the officer could hear--the screaming. The court found that the unannounced, warrantless entry into the house was justified by exigent circumstances: