KANSAS CITY, Mo. -- Major League Baseball could start in-season testing for human growth hormone next year.

Each player was given a blood test for HGH during spring training as part of the labor contract that was agreed to in November, which allows blood testing during the offseason and spring training, and if there is reasonable cause.

Union head Michael Weiner, speaking to the Baseball Writers' Association of America before Tuesday night's All-Star game, said players will be discussing whether to expand testing to the regular season in 2013.

"We have just elected, as we do in June of even-number years, a new executive board, a new group of player reps, and over the second half of the season we'll be trying to generate what the consensus is," Weiner said. "There is at least a possibility, I'm not going to predict which way it's going to go, but there's at least a possibility that we could have in-season testing of some form as soon as next year."

The blood testing that began in spring training could be expanded to the postseason, but that doesn't appear likely to happen this year.

"Every single 40-man roster player was tested for blood this spring. I believe, I'm not certain, but believe that is the most athletes that have ever been tested for blood in any sport at any time, to have 1,200 tests," Weiner said. "What our agreement says is that the parties would get together to discuss the possibility of extending random testing into the postseason. Those discussions will happen at some point at the end of the year."

No major leaguer has been announced as testing positive for HGH. Under the new labor contract the identity of substances that cause positive tests are made public.

HGH is detectable only in blood tests, not in the urine tests that baseball has used since 2004.

Weiner also addressed the case of Milwaukee outfielder Ryan Braun, whose positive drug test last October was overturned by arbitrator Shyam Das after the NL MVP argued the specified collection procedures were not followed. The drug collector didn't take the urine sample directly from Miller Park to a Federal Express office.

Players and management have since rewritten the collection procedures.

"I don't think it was resolved on a technicality. Ryan doesn't think it was resolved on a technicality," Weiner said. "It was a fundamental piece of the agreement that all the procedures have to be observed and they weren't. But that's in the eye of the beholder -- whether you want to call that a fundamental error, whether you want to call that a technicality. What we proved was this was not a valid collection, and therefore collection had to be thrown out, and the case did not proceed to questions beyond that."

Weiner gave his view on Roger Clemens' acquittal last month on charges he lied to Congress following the release of the Mitchell Report. The seven-time Cy Young Award winner repeatedly denied using steroids and HGH.

"Roger Clemens was exonerated legally, but everybody knows, Roger himself, that there's really no winners in that," Weiner said. "He can be exonerated legally and people are still going to think what they're going to think."

The Mitchell Report in 2007 contained allegations from Clemens' former personal trainer, Brian McNamee, that McNamee injected the pitcher with performance-enhancing drugs.

"The Mitchell Report will stand when history judges it as another very constructive step in a process that cleaned up a sport quickly," commissioner Bud Selig said, adding that the Clemens' verdict "is not relevant to me as far as the Mitchell Report."