Its bad enough to make mistakes, worse to make them while representing clients, and even worse when it comes in a legal malpractice case.  Here is a case from Texas where the attorney lost a motion for summary judgment because he did not submit an expert affidavit on time.

Sprowl v. Dooley, No. 05-06-00359-CV (Tex. App.–Dallas May 8, 2007

"Sprowl had hired the law firm of Dooley & Rucker to pursue a defamation case; she later filing a malpractice claim against the law firm of Marshal Dooley and Michael Scott for negligence, fraud, and violations of the Texas Deceptive Trade Practices Act (DTPA).

The defendants moved for summary judgment. Sprowl failed to timely file an expert’s affidavit addressing the standard of care of a reasonably prudent attorney and the alleged causal link between any breach of the duties by her attorney and her claimed injuries. The associate judge granted the summary judgment.

Sprowl appealed the decision to the district court, which heard arguments on December 12, 2005. Three days later, Sprowl filed an expert affidavit of Charles McGarry to support her legal malpractice claims. In February 2006, the district court entered a final judgment, which affirmed the associate judge’s ruling.