Major League Baseball was once heavily criticized for having an extremely weak drug-testing program. Now, the league is instituting a policy that will be the toughest in professional sports.

The MLB and players union have agreed to test for human growth hormone during the season, according to the New York Times. The new deal will require players to undergo unannounced blood tests, as well as a new test that will test for those that are using testosterone.

The news of the expanded performance-enhancing drug policy comes less than 24 hours after the Baseball Writers’ Association of America announced that no former players would be inducted into the 2013 Baseball Hall of Fame class. Former stars like Barry Bonds, Roger Clemens and Sammy Sosa were not elected because of their alleged steroid use.

In November 2011, the MLB and the union agreed to test for HGH, but only in spring training and the offseason. Players had previously expressed concern over how giving blood during the season might affect their on-field performance.

The changes give the MLB, by far, the toughest drug program in American professional sports. The NFL, NHL and NBA don’t currently test for HGH.

Even with the strict policy, the MLB has still suspended some notable players recently. Both Melky Cabrera and Bartolo Colon were suspended for 50 games in 2012 because of failed tests. Ryan Braun was suspended before the start of the season, but his suspension was eventually overturned.