A lack of consistent definition of Penal Code section 273.5 has created a split of opinion as to when a unanimity instruction is required. A 911 caller reported an assault with a tire iron outside and and then they went inside the house. The girlfriend testified that she did not remember the outside events clearly, but that he beat her with his fists after they went inside. The trial court refused the defense request for a unanimity instruction with CALCRIM No. 3500. The prosecutor argued that a guilty verdict could be based on her being hit with a tire iron or with a fist. The appellate court considered whether the circumstances were a continuous course of conduct as one instance or whether the evidence supported two possible bases for the offense. Under the authority of People v. Thompson (1984) 160 Cal.App.3d 220, the beating with a tire iron followed immediately by a beating with a fist would constitute only one violation. Under the authority of People v. Johnson (2007) 150 Cal.App.4th 1467, the jury could have found at least two discrete crimes and they would have been required to determine which beating was the basis for the verdict. Based on the injuries to the girlfriend, the failure to give a unanimity instruction was harmless.