“Trapped” takes viewers into abortion clinics in the South, including June Ayers’s Reproductive Health Services in Alabama. (Chris Hilleke/Abramorama)

“Trapped,” Dawn Porter’s sobering, gracefully constructed documentary about the tide of laws restricting abortion that have swept the country, couldn’t arrive at a more timely moment. Just this week, the Supreme Court heard arguments in a potentially historic case involving a dramatically proscriptive statute passed in Texas. The death last month of Justice Antonin Scalia, which reduced the court to eight judges, makes the ultimate decision all the more consequential: In the event of a tie vote, the existing statute would remain in place.

For viewers interested in the legal and ethical principles at play, “Trapped” provides an intimate, deeply felt primer. The title of the film derives from so-called TRAP laws (for “targeted regulation of abortion providers”), hundreds of which have been passed over the past six years, especially in the South. Following clinics in Mississippi, Alabama and Texas, where abortion providers are required to have admitting privileges at a nearby hospital and where clinics must provide ambulatory surgical services, the film looks behind the curbside protests and legislative fights to examine the effect of these laws on the daily lives of medical professionals and their patients.

The resulting portrait is one of beleaguered but steely determination and occasional confusion, as clinic administrators try to parse arcane and contradictory legal language.

Their tone softens considerably when they must tell a potential patient that there is either no doctor available that week, or that she’ll have to set aside two or three days while she sits out the required waiting period.

“Trapped” makes no pretense of balance. This is an abortion-rights advocacy film, whose thesis echoes the argument offered this week at the Supreme Court: that laws like the ones in Alabama and Texas — several other states have adopted similar measures — impose an undue burden on clinics, thereby vitiating the right to a safe, legal abortion. (Amy Hagstrom Miller, founder of Whole Woman’s Health, the lead plaintiff in the Supreme Court case, is interviewed in the film.)

Porter, who previously directed “Gideon’s Army,” about public defenders, is both direct and discreet in filming a subject that doesn’t readily lend itself to expressive visual language. Most of the clinics’ clientele are photographed only at ankle level, the camera occasionally glimpsing clasped or resting hands. The protagonists of “Trapped” are the clinic directors and doctors who have come to see reproductive health less as a profession than a calling. The most fascinating figure is physician Willie Parker, whose practice is animated by his Christian ethics and who can be seen moving his practice from Illinois in order to attend underserved patients in Mississippi, Alabama and Georgia.

Like “After Tiller” a few years ago, “Trapped” is lucid and illuminating about the issue of abortion as a constitutional right. But in addition to being instructive, it brims with compassion, leaving viewers with haunting images of women we never even got to see in the first place. At one point, a 13-year-old rape victim is told that she won’t be able to get an abortion in her state, meaning she would have to get the time, money, family support and resources together to travel thousands of miles. As the clinic worker says, she’s basically been “sentenced to motherhood.” Porter leaves viewers with the haunting question of what happened to that girl, where she is now, and what we did to get her there.

Unrated. At Landmark’s E Street Cinema. Contains mature thematic material. 83 minutes.