The Canon of Laws was the system that determined the entire Sikarian system of values. They believed that to break even one precept, to allow even one exception to the law, would undermine everything they believed in.
Regardless, according to Jaret Otel, many people believed that rules should be flexible enough to meet the needs of the moment.
In 2371, the USS Voyager attempted to acquire a spatial trajector from the Sikarians in an attempt to shorten their journey back to the Alpha Quadrant. Unfortunately, the Sikarian magistrate, Gathorel Labin, denied Captain Kathryn Janeway's request, as it would have violated their Canon of Laws. (VOY: "Prime Factors")