You shouldn't ever sign someone else's name to anything, but chances are good that you've done just that at some point. Did you know that doing so can lead to a criminal charge of forgery? This is a very serious matter that cannot be ignored.
Forgery can take a couple of different forms. One of these is if you were signed someone's name on personal documents in an effort to steal that person's identity. This type of forgery is especially egregious because of the negative repercussions of identity theft. This crime can cost victims thousands of dollars and take many years to correct.
Another type of forgery involves creating documents in an attempt to make money or for other purposes. This is commonly done on historic documents and sometimes executed on various types of statements. Some people might even try to forge legal documents, which can lead to very serious legal issues.
Even if you have another person's permission to use his or her identifying information or sign off on documents, it is not wise to do so without a valid agreement in writing stating just that, as when you have another person's power of attorney. Without it, you risk the person claiming that he or she never gave you that permission. If this does occur, you could be in some serious trouble.
In business situations, there can be instances where this occurs, such as secretaries signing forms in executives' stead. This should always be done with a clear notation that the person who actually signed the documents was authorized to do so. This can prevent legal issues from arising later.
Source: FindLaw, "Forgery," accessed Sep. 08, 2017