The criminal justice system often relies on forensic evidence to convict or acquit the accused, but some legal experts say many forensic techniques, including bite-mark, ballistic and hair analysis, lack scientific credibility. Even when forensic methods, such as DNA analysis, are scientifically valid, they often have error rates far higher than juries are led to believe. Prosecutors, however, defend forensic methods as reliable and proven by long-standing practice. They worry that if forensics is undermined, convicting criminals will be much harder. Still, both sides agree that the methodology behind many forensic tools can be strengthened by improving the underlying science. In Texas, which was once heavily criticized for weak oversight of forensic practices, a newly reorganized commission is working to improve forensic science in the state. Meanwhile, the FBI is reconsidering its hair-analysis standards following a scandal that triggered a massive post-conviction review of 2,500 cases in which the agency's lab provided sometimes flawed hair-matching evidence.