This book offers the first quantitative study of decision-making on the UK Supreme Court. Covering the court's first ten years, it examines all stages of the court's decision-making process—from permission to appeal to the decision on the final outcome. The analysis of these distinct stages shows that legal factors matter. The most important predictor of whether an appellant will succeed in the Supreme Court is whether they've been able to convince judges in lower courts. The most important predictor of whether a case will be heard at all is whether it has been written up in multiple weekly law reports.