"Most programs that create documents, including Microsoft Word and other Microsoft Office products, save metadata with the document files. These metadata can contain the name of the person who created the file (obtained from the operating system), the name of the person who last edited the file, how many times the file has been printed, and even how many revisions have been made on the file. Other saved material, such as deleted text (!!) (saved in case of an undelete command), document comments and the like, is also commonly referred to as "metadata", and the inadvertent inclusion of this material in distributed files has sometimes led to undesirable disclosures."--Wikipedia
The implications that metadata can have on a legal case are enormous. In fact, apparently some cases, after metadata had been discovered and then applied to documents in closed cases, have been completely overturned(the DNA of documents?). That is amazing. Who would've thought? So next time you exchange those anger-charged words for nicer euphemisms, or sneak in a change in a document, be on the alert. Could come around to bite ya in the arse.
It is also interesting to note that since the whole metadata discovery has come about, lawyers apparently are using Adobe Acrobat (a program which can either be manipulated not to store it, or does not allow it, or just shows the changes outright--I'm not quite sure yet which or if all) when exchanging documents such as contracts with the opposing lawyers, say during negotiation. Whether it is stored in e-mails, I cannot say but I would like to find out.