Are signature stamps legal for use in signing documents and checks and who is responsible for check fraud?

The point of a signature is to indicate the signer's intent and exercise of discretion in making the signature. The mechanics of making the mark are less important.

In general, unless a jurisdiction has adopted a statute specifying specific requirements as to how a signature can be made someone can sign a document in many different ways. This includes facsimiles and rubber stamps. The signer can create the facsimile using the stamp or can authorize someone else to use the stamp in the signer's presence.

Some feel that using a stamp for a signature is impractical. The stamps could be lost or stolen. This would allow someone possessing the stamp to seemingly sign someone else's signature. However, in the absence of that person's intent and discretion such a signature is probably invalid from a legal perspective. Still, it might be a burden to fix such a situation. Critics of the stamp approach note that signing by hand may even take less time than inking the stamp and applying it to the document.

That said, many people and businesses routinely use stamps or other mechanical methods to endorse checks and sign documents.

You can read more about this concept in a legal encyclopedia such as 80 Corpus Juris Secundum, Signatures, sections 2 through 7.