The law on which handwriting identification is based is: Handwriting Identification Standard for Judicial Identification. Handwriting identification refers to the identification and recognition of handwriting formed by people through writing activities. People's writing habits are specific and stable, and are reflected in handwriting. Through the examination of handwriting, we can determine whether the handwriting in the document was written by several people or by someone, and use handwriting to identify the same person and verify the authenticity of the document. Handwriting identification can not only test normal handwriting, but also test handwriting with changing writing conditions (including writing posture, writing tools, padding, etc.), intentionally disguising handwriting (including left-handed handwriting and ruler-drawn handwriting), imitating handwriting and painting handwriting. When the same person writes with the same pen, the characteristics of pen marks can also be used to enrich the basis for identifying the writer.