NASHVILLE (AP) — Expert witnesses on Wednesday presented dueling views of whether Tennessee's 48-hour waiting period before abortion helps or hinders women's decision making.

Five of Tennessee's seven abortion clinics are suing in federal court in Nashville over the law, which requires women to make two separate trips to an abortion clinic, first for mandatory counselling and then for the abortion.

Testifying for the state Wednesday, Priscilla Coleman, a psychology professor at Bowling Green State University in Ohio, said research shows women seeking abortion face "fairly high levels of ambivalence and uncertainty" and a number of them experience significant stress.

Although laboratory studies concluding decision making under stressful conditions benefited from a short wait are not "directly analogous" to abortion decisions, Coleman said, she still concluded that, logically, women should be given time to make a decision about abortion.

"I think we want every woman to be as certain as possible," she said.

Jeffrey Huntsinger, a social psychologist at Loyola University Chicago, said some of the studies Coleman relied on were irrelevant and others were misinterpreted.

Huntsinger testified that studies relevant to real-world decisions like abortion have found that stress and emotions can help people make good decisions. He also said research shows that individuals are good at figuring out how long they need to make a decision and forcing them to continue deliberating after that can lead to worse decisions.

In determining whether Tennessee's waiting period violates the U.S. Constitution, U.S. District Judge Bernard Freidman must determine whether it places an undue burden on women seeking abortion. It's a subjective standard that has caused some waiting period laws to be struck down and others upheld, depending on the specific circumstances of the state.

The clinics claim the law has no benefits for women. Clinic directors previously testified the wait period causes women financial hardship and stress. They also said the two-visit requirement poses logistical challenges for patients and clinics that cause abortions to be delayed far beyond the 48 hours required by law, pushing some women into surgical abortions, which have greater risks of complications.

Alex Rieger of the state attorney general's office defended the law in opening statements Monday. He said the waiting period "offers women a chance to make a different choice." He said the law provides a commonsense approach to promoting the state's legitimate interest in fetal life.

Tennessee is one of 14 states with laws requiring women to make two trips to an abortion clinic according to the Guttmacher Institute, a research group that supports abortion rights.