PORTLAND — An Evangelical Shapleigh couple and two of their seven children are challenging a Portland city ordinance preventing protests within 39 feet of an abortion clinic, arguing in a lawsuit filed Wednesday the buffer zone is an infringement on their constitutional right to free speech.

The lawsuit was filed in U.S. District court the same day as the city was dealt a defeat in another federal First Amendment case. U.S. District Court Justice George Z. Singal ruled on Wednesday the city overstepped its bounds and unnecessarily curbed the free speech rights of panhandlers and political activists when it passed an ordinance prohibiting people from standing in median strips.

Demonstrators upset about the Portland buffer zone hope they’ll get a similar ruling in their case — which comes about a month after the U.S. Supreme Court heard arguments in a comparable legal dispute over 35-foot bubbles around Massachusetts abortion clinics.

Leaders of Planned Parenthood of Northern New England, which operates the 443 Congress St. clinic at the heart of the Portland ordinance, had been watching the Supreme Court case closely, expecting that the high court’s ruling would either cement a precedent in favor of such buffer zones or cast them as vulnerable to legal challenge.

But Shapleigh couple Daniel and Marguerite Fitzgerald, in their own right and on behalf of two of their seven children, sued the city on Wednesday without waiting for a Supreme Court precedent to cast a shadow one way or the other over the Portland case.

The Fitzgeralds described themselves in their lawsuit as Evangelicals who are raising their children in the faith. They name the city of Portland, Mayor Michael Brennan and each of the other eight city councilors by name as defendants.

In November, the City Council unanimously approved the 39-foot buffer to push back demonstrators who had been gathering weekly outside the Planned Parenthood for about a year to protest the abortion activities at the site. The bubble effectively forces the demonstrators to gather across Congress Street from the clinic.

Planned Parenthood representatives argued before the council that patients, many of whom were not going to the clinic to seek abortions, were feeling harassed and intimidated by the protesters, and that the buffer zone was necessary to preserve those patents’ legally protected rights to access health care.

Protesters, some of whom represented the group Pro-Life Missionaries of Maine, countered that their behavior was being blown out of proportion, that the lack of any arrests from the regular demonstrations showed that they’d been peaceful and law-abiding, and that the activity is protected speech as defined by the First Amendment.

In their lawsuit, the Fitzgeralds reiterate many of those same arguments.

“[The Fitzgeralds] are faithful Evangelicals motivated to oppose the practice of abortion because of their religious beliefs that abortion is the deliberate destruction of innocent human life,” their attorney, Stephen Whiting, wrote in his complaint. “[They] peacefully pass out literature and Bible tracts in accordance with their faith and in efforts to counsel women seeking abortions. Prior to the ordinance, [they] regularly provided information to women about abortion alternatives, assistance and support to persons entering and/or exiting the facility.”

The Fitzgeralds go on to argue that individuals stop within the buffer zone to socialize, smoke cigarettes or — on at least one occasion — demonstrate in support of the clinic, and that those activities could be difficult to legally differentiate from what they wanted to do in that same space.

“Because a police officer cannot know with certainty whether a person is using a public sidewalk or street ‘solely’ for the purpose of reaching a destination other than a reproductive health care facility, the ordinance authorizes and encourages arbitrary and discriminatory enforcement,” the lawsuit reads, in part.

Representatives of Planned Parenthood and the city of Portland did not immediately respond to requests for comment late Wednesday night.

On previous occasions, Planned Parenthood officials and clients have argued that the language and approach used by the anti-abortion protesters was confrontational and threatening.

One patient told the council in November a demonstrator told her he would “bound me at the knees and lower me into a lake of fire,” and on another occasion, that he would “wipe that smile off my face.”

The weekly anti-abortion protests triggered a counter-protest last winter organized by area businessman Mike Fink, and the early January protest duel over abortion rights attracted widespread media attention.

Fink blamed the regular demonstrations for driving away foot traffic to his nearby restaurant, which he ultimately closed in August.

The nonprofit Planned Parenthood has been a target of anti-abortion activists nationwide because of the organization’s advocacy for reproductive rights. Some congressional conservatives have similarly fought to eliminate federal funding for the organization over the years because it provides information about — and in some cases performs — abortions.