What are the circles after fence work and how are they judged?

The circles in working cow horse follow the fence work and require the horse to drive the cow in arcs in both directions — circling it to the left and to the right — demonstrating the horse's ability to control the cow's direction in open arena rather than at the fence. The circles are the final phase of the cattle run and are evaluated on the horse's ability to drive the cow in a consistent arc, maintain position relative to the cow throughout the circle, and demonstrate that the horse can control the cow's movement directionally as well as linearly along the fence. Correct circling position places the horse at the cow's outside hip or shoulder — on the outside of the arc the cow is making — so that the horse's pressure keeps the cow moving in the circular path rather than allowing it to straighten and escape. A horse too far behind the cow during circles cannot influence its direction; a horse too far ahead of the cow pushes it into a tighter circle or stops its forward movement entirely. Judges evaluate the circles for the horse's control of the cow — whether the arc is consistent or whether the cow is determining its own path with the horse simply following — the correctness of the horse's position relative to the cow throughout each circle, and the horse's athleticism in maintaining that position as the cow changes pace or attempts to straighten and escape. The difficulty of the cow during the circling phase — how athletic and resistant it is to being circled — also influences the credit given, with correct circling of a difficult, fast cow earning more credit than the same technical quality of position on a slow, cooperative cow.