By Cherri Gregg

PHILADELPHIA (CBS) — A new law in Pennsylvania will allow experts to testify at trial about the impact of sex abuse.

“This information could be critical to a prosecutors case,” says Carol Tracy, Executive Director of the Women’s Law Project.

She says the new law levels the playing field by providing critical information on why sex abuse victims sometimes don’t report crimes right away or don’t exhibit emotion when discussing the crime.

“Explanation of victim behavior and disposing of all the stereotypes of victim behavior is a major step forward,” Tracy says.

Philadelphia defense attorney Richard Disipio says the testimony will unfairly bolsters the credibility of abuse victims.

“You have someone who wasn’t there, didn’t know about the case and they’re going to give an opinion as to why someone didn’t report,” says Disipio. “Let an intelligent jury decide whether they believe the victim or not.”

Pennsylvania was the only state in the union that did not allow experts to provide insight on similarities among sex abuse victims. Representative Cherelle L. Parker (D- Philadelphia) sponsored the law, which took six years to pass, and says it could have been helpful in the Jerry Sandusky and priest sex abuse trials.

“I do believe that those two high-profile cases brought the attention that was needed to get the legislature and the public to understand how outdated and antiquated Pennsylvania’s laws were,” Parker says.

The law was expected to take effect in August.