[2] At Proctor High School in Utica, Smith was a USA Today All-American pick, and was rated by Prep Football Report as the best defensive line prospect in the state.

[citation needed] Smith was a four-year letterman at Ohio State from 2000 to 2003, he helped lead the Buckeyes to the 2002 BCS National Championship, and he was named a first-team All-American the following year.

In 2005, he had 48 tackles and 8.5 sacks and played well enough that the Saints did not re-sign Darren Howard thus making Smith the starter opposite Charles Grant for the 2006 season.

Smith played in 14 games, sitting out the finale with the Saints having clinched a playoff berth and also missing one contest with a knee injury.

[5] On December 2, 2008, Smith was one of six players suspended for use of Bumetanide a diuretic, which can be used as a masking agent for steroid use.

Smith's original punishment was announced as a four-game suspension, covering the final four games of the 2008 regular season.

[7] Smith's suspension was later reduced to a two games and an additional two lost paychecks, and was served at the beginning of the 2011 NFL season.

[8] Under new defensive coordinator Gregg Williams in 2009, Smith had a career high 13.0 sacks, 49 tackles, 3 forced fumbles, and one interception.

On May 2, 2012, Smith was suspended by the NFL for the first four games of the 2012 season because of his alleged role in the New Orleans Saints bounty scandal.

However, Smith suffered a knee injury (a torn ACL) in the Saints' third preseason game, against the Houston Texans on August 25, 2013, and was reported to be out for the season.

Results of a postmortem toxicology report concluded that Smith had a blood alcohol content of .235 on the night of the incident, or nearly three times the legal limit in Louisiana.

[33] Three years to the day after Hayes was sentenced, however, the United States Supreme Court handed down the Ramos v. Louisiana ruling, which declared that non-unanimous criminal convictions violate the Sixth and Fourteenth Amendments.

[35] On January 27, 2024, Hayes was found guilty of manslaughter at his re-trial where he faces up to 40 years in prison.