科幻大師艾西莫夫Isaac Asimov曾寫下很知名的機器人三定律：
1. A robot may not injure a human being or, through inaction, allow a human being to come to harm.
2. A robot must obey any orders given to it by human beings, except where such orders would conflict with the First Law.
3. A robot must protect its own existence as long as such protection does not conflict with the First or Second Law.
- 機器人不得傷害人類，或袖手旁觀坐視人類受到傷害；
- 除非違背第一定律，機器人必須服從人類的命令；
- 在不違背第一及第二定律下，機器人必須保護自己。
結果，最近有美國鄉民發現知名音樂社群網站Last.fm居然把三定律寫到他們站內的robots.txt裡去了。
Last.fm此舉顯然把美國鄉民逗得歡樂到不行。