In general, once you sign a plea deal, you may not change your mind. However, you may be able to challenge the plea deal if you entered into the agreement because: Your lawyer was incompetent (ineffective assistance of counsel); You were mentally ill or otherwise legally incompetent when you signed the agreement; or The police or prosecutor committed fraud in connection with your case. You should be aware, however, that such challenges to plea bargains are rarely successful absent clear evidence that you were unable to understand the consequences of what you agreed to.