BOSTON — In the wake of the recent U.S. Supreme Court ruling striking down buffer-zone limits as a violation of the First Amendment, the American Civil Liberties Union of Massachusetts says that decision bolsters its argument that Lowell’s ordinance banning panhandling downtown is unconstitutional.

But the city argues in court documents filed late last month that the Supreme Court ruling last month is “irrelevant” to the city’s ordinance and that a federal Appeal’s Court decision involving the city of Worcester’s panhandling ordinance, Thayer v. City of Worcester, favors the city’s position banning “aggressive” panhandling.

Now it is up to a federal judge to decide.

No hearings before U.S. District Court Judge Douglas Woodlock have been scheduled as yet.

The ACLU of Massachusetts, with Goodwin Proctor LLP of Boston, filed a lawsuit in U.S. District Court after the City Council toughened the panhandling ordinance by banning panhandling in the downtown district last November, then amended it again in February to ban “aggressive panhandling,” which involves following and accosting people.

Last week, the New Hampshire Civil Liberties Union announced it is suing the Hudson, N.H., Police Department, alleging that the town and its officers engaged in a pattern of harassing panhandlers in that town, a violation of their rights. An effort to pass a panhandling ordinance in Hudson last winter failed.

During the first 11 months of 2013, Lowell police received 237 calls related to panhandling, and some councilors said panhandling was becoming a growing problem in the city.

Police observing anyone aggressively panhandling in the Downtown Historic District could arrest them. The approved ordinance stipulated that violators could be found guilty “for each day during which the violation is committed, continued or permitted.”

Upon conviction, each offense can be punishable by a $50 fine. The Police Department can also issue noncriminal dispositions with a $50 penalty per violation. Those penalties would remain in effect.

The revised ordinance also eliminates the exemption to the law for nonprofit agencies, civic or benevolent organizations described in Section 501(c) of the Internal Revenue Code.

The ACLU sued on behalf of three homeless men living in Lowell — Randy Copley, Kenneth McLaughlin and Joshua Wood — challenging the city’s ban on panhandling within 400 acres of the Downtown Historic District because it violates the First Amendment right to free speech.

After a hearing in federal court in April, Lowell officials told Woodlock they would voluntarily suspend enforcement of the city’s panhandling ordinance if Woodlock agreed to postpone a decision on an injunction against the city and wait for the U.S. Supreme Court’s ruling on abortion-clinic buffer zones and the Thayer decision.

In its June decision, the U.S. Supreme Court struck down a Massachusetts law that banned protesters within 35 feet of abortion clinics, ruling that the law infringed upon the First Amendment rights of antiabortion activists.

The decision effectively overturned about 10 fixed-buffer-zone laws across the country, from San Francisco to Portland, Maine, but offers a framework for more limited restrictions around clinic demonstrations, legal experts said.

The high court ruled that the state law, enacted in 2007, imposed “serious burdens” on protesters who wish to speak with arriving patients.

Relying on the buffer-zone decision, the ACLU writes that the downtown, which is described as Lowell’s historic district, is, in effect, “an enormous buffer zone, must larger than the 35-foot buffer zone struck down” by the Supreme Court.

The ACLU wrote that the city’s ban on aggressive panhandling is targeted only at particular speech — that requesting an immediate donation of funds.

“Someone requesting a donation can stand side-by-side near a downtown bus stop with someone asking to sell an item for market value, and only the person requesting the donation can be asked by police to stop and be arrested if he refuses,” the ACLU writes.

“Lowell argues that its law is content-neutral,” but as the buffer-zone decision confirms, “Lowell is clearly wrong.”

The ACLU continues, “Lowell plainly seeks to justify its ordinance on listeners’ reactions to speech including offense or discomfort caused by solicitations for charity and the undesirable effect of offending tourists.”

But in another decision, Thayer v. City of Worcester, issued weeks after the buffer-zone ruling, the city of Worcester argues that the ACLU’s motion for an injunction against its panhandling ordinance should be denied.

The city argues that remarks by city councilors in Worcester cannot be interpreted as discriminatory when it comes to panhandling. The ACLU attached to its lawsuit against the city records of the Lowell City Council’s proceedings.

“The city’s aggressive-panhandling ban, like Worcester’s, is based on the selfsame interest of avoiding the fraud and duress that are legitimate municipal concerns,” the city wrote.

The Worcester ordinance and the Lowell ordinance are identical as to the definition of solicitation and of aggressive panhandling, Lowell officials wrote.

Follow Lisa Redmond on Tout and Twitter@lredmond13_lisa.