Catherine Cortez Masto is a Democratic senator from Nevada. The opinions expressed in this commentary are solely her own. View more opinion articles on CNN.

(CNN) Imagine that you're walking down the street in your neighborhood when you see your ex-boyfriend lurking near your apartment building. The next day, you see him at your workplace. Soon, he's everywhere, and witnesses can testify that he's following you. But your stalker goes free because your town doesn't have the power to prosecute the person who is shadowing you. How safe would you feel?

Catherine Cortez Masto

Unbelievably, Native American women and girls face exactly this situation on tribal lands in America. In 1978, the Supreme Court ruled that tribes could not prosecute non-members. In other words, if the person who stalked -- or beat or raped you -- was not a tribal member, he was unlikely to face justice. For many Native Americans, it was like the Supreme Court said that your town could only punish your stalker if he was also from that town.

In 2013, Congress made changes to the Violence Against Women Act (VAWA) to let some tribes prosecute non-tribal members for domestic violence. Here's how it works: Tribes that want to go after domestic abusers on tribal lands ensure that their laws are in line with what the Constitution requires. These tribes must show that they will protect defendants' rights: they have to offer low-income defendants a lawyer, choose a qualified judge, guarantee trial by an impartial jury, and observe other aspects of a fair process for trying these cases. As of June, there were 25 tribes all over the country prosecuting domestic violence cases, and they had secured over 70 convictions.

But there are still major gaps in VAWA's protections that this Congress needs to fill. Currently, the law doesn't allow tribes to go after rapists, stalkers, or other criminals. It doesn't permit them to protect children from domestic violence. And, incredibly, the law doesn't let tribes step in if a tribal police officer gets assaulted.

These gaps are so harmful because Native Americans deal with higher levels of violence. According to a National Institutes of Justice (NIJ) report, 84% of native women have experienced rape, domestic violence, stalking, or aggression in the course of their lives. A heartbreaking half of them have been assaulted by an intimate partner. And for more than a third of the 84%, these events are fresh -- within the last year.

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