A proposal to enhance legal protection for pregnant women by hardening the punishment for harming them deserves discussion at next year's lawmaking session, but there are several key points that discussion must cover.

The idea, which would be introduced in the 2008 legislative session, is being floated in various forms by state Reps. Tommy Waters and John Mizuno, who hope the protection won't create a slippery slope, whittling away a woman's legal right to terminate a pregnancy.

No bill has been written yet, but in general the approach would be to punish attacks that result in a miscarriage, placing the focus on the pregnant woman rather than on the fetus.

The idea is that pregnant women can be considered a protected class in the event of an assault or homicide case, in the same way assaults on elders and children can draw a stiffer sentence as a means of protecting a vulnerable class.

In the context of domestic violence, that concept has some merit. Statistics do indicate that a pregnant woman in an abusive situation is at greater risk of physical harm while she is pregnant. The Centers for Disease Control and Prevention has set the estimate that 4 to 8 percent of pregnant women report being victims of violence.

Waters said he was struck by the Big Island case of Tyrone Vesperas, who allegedly stabbed his estranged wife. Her unborn child did not survive, and the couple's 14-year-old son also was stabbed to death.

Arguments pro and con are already stacking up. Critics say Hawai'i statute already allows for enhanced sentencing, even in cases less heinous than that. Others, including state Attorney General Mark Bennett, argue that the current law may exclude some cases of miscarriage as evidence of felony injury that qualifies for harsher penalty.

That question — Is added legislation needed to protect pregnant women? — should be debated and settled.

Another point of contention: Could such a law, in which fetal death is a criterion for weighing the injury, water down abortion rights? Waters and others say no, but both sides must be carefully examined.

Other aspects could be problematic. An assailant's intent is key; at what point could or should an attacker know a woman is pregnant?

Creating a separate class for treatment under the law should be done with caution. Let's make sure that some unintended effects of the law don't outweigh the benefits.