The study developed a theoretical framework, referred to as the custody-threshold thesis, that considers the decision to arrest to be a function of the officers' goals to satisfy one of several purposes of custody. Restraining-order violations in domestic violence incidents had the greatest impact on arrest probability when risk of injury to the victim was low. As that risk increased, the predictive strength of restraining-order violations diminished. This study clearly shows that altering the police decision to arrest is more challenging than simply issuing a restraining order. Although the presence of a protective order appeared to have a strong impact on police arrest patterns, that impact was observed under very specific conditions. Therefore, findings suggest that any inquiries attempting to explain the police arrest decision should be considered in terms of custody thresholds. Although police may place a great deal of importance on the preventive purpose of custody, they appear to have marginal regard for the less urgent functions, such as the administrative. Tables, notes, references