Does a fake signature have legal effect? How to investigate the legal responsibility of false signature?

It is illegal to impersonate others to sign, and the consequences are at your own risk. According to the contract law, the contents of the contract agreement should conform to the national laws and embody the principles of fairness and justice. Both parties need to sign in person, and the information of the parties should be true and effective. Therefore, the agreement signed by impersonating others is false and invalid.

Legal basis: Article 111th of the Civil Procedure Law of People's Republic of China (PRC). If a litigant participant or other person commits one of the following acts, the people's court may impose a fine or detention according to the seriousness of the case; If the case constitutes a crime, criminal responsibility shall be investigated according to law: (1) forging or destroying important evidence, which hinders the people's court from hearing the case; (2) using violence, threats or bribes to prevent witnesses from testifying or instigating, bribing or coercing others to commit perjury; (3) Hiding, transferring, selling off or destroying the property that has been sealed up or detained, or transferring the property that has been counted and ordered to be kept; (4) Insulting, slandering, framing, beating or retaliating against judicial personnel, participants in litigation, witnesses, translators, expert witnesses, inspectors and assisting executors; (5) Obstructing judicial personnel from performing their duties by violence, threat or other means; (6) Refusing to perform a legally effective judgment or ruling of the people's court. The people's court may impose a fine or detention on a unit that commits one of the acts listed in the preceding paragraph; If a crime is constituted, criminal responsibility shall be investigated according to law.