HARRISBURG, Pa.—The state House of Representatives on Thursday night approved a bill to allow expert witnesses to testify for the prosecution in rape cases and sent it to Gov. Tom Corbett, who is expected to sign it.

The bill, which was approved without debate, will end what proponents said is Pennsylvania's stigma as the only state without such a law.

Sponsors said the legislation will allow experts to help victims at trial by describing for jurors the dynamics of sexual violence and—for example—offer possible explanations for why a victim did not immediately report the attack to police or go to a hospital.

In an editorial Thursday, the Philadelphia Daily News urged passage of the bill and questioned whether how such a law might have affected the ongoing child sex-abuse trial of former Penn State assistant football coach Jerry Sandusky.

"This is a bipartisan victory," said Rep. Cherelle Parker, D-Philadelphia, who joined with co-sponsor Rep. Kate Harper, R-Montgomery, in thanking their House colleagues.