“What if it is customary there to leave the doors unlocked?” asked Mrs. Kohn.
“In that case, a shomer chinam [unpaid guardian] would be exempt,” answered Rabbi Dayan. “He is expected to watch in the normal, customary, manner. Similarly, if you had gone out for a short time to get a cup of coffee, when many people leave the office unlocked, you would be exempt. However, a shomer sachar [paid guardian] is still liable. He is paid to provide extra protection.” (C.M. 291:8; 303:10-11)
“What if Mrs. Kohn herself would often leave her door unlocked?” asked Mrs. Melamed. “Can I be expected to watch better than she does?”
“This case is not commonly addressed,” replied Rabbi Dayan. “It seems, though, that a guardian is required to guard according to what is commonly expected. Thus, you cannot exempt yourself by claiming that Mrs. Kohn often leaves her office unlocked.”