A horizontal audit is a means of following a process from start to finish. It's a comprehensive, objective and systemic review of a lab's planning, organizational, directing and control processes. Planning: objectives and administartion practices; Organizing: delegation of responsibility; Directing: supervision, communication, training & development; Controlling: evidence control, quality manual, quality system review, procedures/materials/equipment... case documentation & review, court testimony monitoring, annual audit, quality manager and proficiency testing. An audit covers all these areas of a lab.