Can the rules (sīla) ever be broken?
戒条是可以开的吗？

Among the precepts in Pātimokkha, apart from the four fundamentals of no killing, no stealing, no sexual conduct and no lying on spiritual attainment, all the rest should be maintained in general, but can be relaxed under certain circumstances. According to the Bodhisatta Rules, all must serve the needs of benefiting sentient beings (Sattvārtha-kriyā sīla). Thus for lay Bodhisattas, even the four fundamentals may be relaxed as required for benefiting sentient beings. "Maintain" and "relax" are the terminology used in Vinaya texts. For instance, abstention from eating after midday must be observed in normal times, yet in case of illness, it can be broken if the afflicted need to take food after midday. The Chinese monks have to relax the precept of not eating after midday because they take part in farm work. In the temples of the Zen Sect, supper is called "chamber meal", since it was originally provided to the laborers in their rooms instead of in the dining hall. However, in later times, those who did not take part in labor also began to have supper.
比丘戒中除了不杀不盗不淫不妄四根本戒外，其余戒条平时应当“遮护”，在一定的情况下可以“开”（菩萨戒，一切服从“饶益有情戒”，在家菩萨为饶益有情故，四根本戒也可以开）。“开”与“遮”是戒律上的术语。如以过午不食为例，平时应当遮，但遇有某种疾病，必须午后进食的人则可以开。我国僧人因劳动的缘故必须开过午不食的戒。禅宗寺庙把吃晚饭叫做房餐，本来是给参加劳动者在房里吃的，而不是在斋堂中大家吃的，但是后来不劳动的人也吃起晚饭来了。