My ex-wife just called me to assure me that her brief was mailed on time, and she didn't just sit on it for a week. She blamed the problem on the post office.
She said that her law firm has this problem all the time. They put mail in an outgoing mail basket, and someone else is supposed to mail it. When the opposing law firm doesn't get a brief on time, it just calls and asks for another copy. Her firm just emails or faxes the document, and it is no big deal. I should have called and asked, she said.
She said that she hand-delivered the brief to the court on the day after she was to have mailed it to me. I guess that she didn't trust the post office to get the brief to the court on time.
I actually believe her when she says that she didn't hold up the brief. If she were going to use such tactics, then there were other situations where she would have had more to gain. But I am also skeptical that the post office is really that slow. Maybe her law firm employs a goof-off mail clerk, I don't know.
The real problem is that the court uses such an outmoded system for handling paper documents. The court should just use a system of electronic filings. The court and the opposing party would necessarily get the same document at the same time.