Encopresis is the leaking of stool without knowledge of the person. It is most common in children and the elderly, and is caused by unrecognized and uncontrolled constipation. The chronic constipation causes pressure on the rectum allowing some leakage to occur.
It can be treated by a physician with a combination of high fiber diet and a daily stool softener - not a laxative - to reduce the constipation. Children can be taught to recognize the correct sensations that accompany a bowel movement and often grow out of the problem.
The elderly can have chronic issues because of limited mobility, damage from stroke or other illnesses, and the results of long term constipation. It's important to realize that they really have no sensation or control over the problem and need to be handled with patience and discretion.