In criminal fraud cases entries that are computer generated are now the norm. However, in medical practices, handwritten entries are still common and the handwriting in medical records/charts often differs markedly from the the day to day, non-business handwriting of a physician. Experts often look to see who saw a patient and then assert that the handwriting on a chart belongs to the same physician (or PA). This shortcut is not permitted under the Evidence Code and handwriting statutes are very specific regarding the methods that can be used for identification. Here is some of the law on handwriting identification.
Evidence Code Section 1413 allows a writing to be authenticated by a person who saw the writing made or executed, including a subscribing witness.
Evidence Code Section 1414 A writing may be authenticated by evidence that the defendant admitted the authenticity of the document. (1414 (a)) Alternatively, the prosecution can show that the defendant acted upon the document as “authentic” (1414 (b))
Evidence Code Section 1415 states that “[a] writing may be authenticated by evidence of the genuineness of the handwriting of the maker.” Again, it is not the authenticity of the document that is at issue but the identification of handwriting as belonging to a particular person.
Evidence Code section 1416 states that a witness who is not otherwise qualified to testify as an expert may state his opinion whether a writing is in the handwriting. However this section requires personal knowledge of the verified handwriting of a person and some basis to opine that the questioned writing also belongs to that person.