Legal documents should be handled as a business or professional document. This includes using the proper technique for folding the document before it is mailed. Folding a specific way may seem unimportant, but it shows a level of professionalism and sophistication equivalent to a speaker's use of proper grammar. Legal documents are much more professional than a letter to Mom, and taking the time to fold them professionally may help you to be taken more seriously.
According to Englishplus.com, the correct way to fold a business letter is to fold it twice into horizontal thirds, starting with the bottom half, then folding the top half over so that the text faces in. The bottom fold should actually be slightly more than a 1/3 fold; the top will fold down to slightly less than a 1/3 fold. When finished, any recipient of your mail will simply have to flip open the top half to see the sender's name and contact information, assuming you have properly headed the business letter.
Proper placement of documents in an envelope is the final stage of disclosing your documents. Dixie, at savvy-business-correspondence.com, demonstrates that the letter should be placed facing the back of a #10 envelope so that the receiver can easily lift the fold that will show the top of the page and the sender. Consider that legal offices and courts receive many types of correspondence on a daily basis. Your extra consideration in folding and enveloping your documents will make it so that the recipient can flip the envelope over, pull out its contents, and open to the heading of your correspondence with ease.
For businesses or individuals who mail a lot of legal documents on a regular basis, an investment in a letter folding machine may be a wise decision. It can be difficult to fold papers with even lines and consistency. Using a machine will give you consistent results and save you time.