Gross mass misconceptions underline the need for detailed and well written legal documents. Take for example the "new" decade of 2010-2019. In fact, we are not yet in the new decade, which does not begin until 2011. This is because there was no year "0". Before the year "1" AD there is the year "1" BC. Thus, the first year in the modern calendar is year "1". Which means the first decade, the first ten years, ended at the end of year "10", and the second decade did not begin until the year "11". Accordingly, the second millennium did not begin until 2001, and the second decade in the second millennium does not begin until "2011". Nevertheless, largely because of the ignorance of the media, everybody believes the second decade has begun.
What is the significance of this? That errors in dates and deadlines are extremely common and constant vigilance in drafting legal documents is required.
Law is beset by legal deadlines and drop dead dates. Intellectual property law is no exception, and in fact has more than the average number of kill dates, with very dire consequences. Just by way of a few examples, for patents there is the one year statutory bar deadline, the one year conversion from provisional to nonprovisional deadline, the one year foreign application filing deadline, the 20 and 30 month national stage filing deadlines, the six month response deadlines, etc. (By the way, the large number of myriad kill dates in patent law are a good reason why inventors should not go it alone). A particularly knotty deadline is appealing de novo a BPAI decision, which must be done within two months. Many practitioners assume that "two months" means 60 days, with 30 days a month. But in fact, the two months means two actual months. Thus, if the two months after the decision include a month that has 31 days, then the appeal can be, for example, in 61 or 62 days (if there are two months sequentially of 31 days each, like July and August).