A federal judge in Philadelphia is refusing to throw out charges against a 30-year-old woman believed to have had plans to move to Syria and martyr herself on behalf of the Islamic State group.

Lawyers for the defendant, Keonna Thomas, claimed that her Twitter activity should be protected under the First Amendment and that prosecutors didn't have enough evidence to prove that she was seriously trying to join the terrorist organization.

Federal District Judge Michael Baylson ordered on Thursday that the motion to dismiss be denied because providing "material support," which courts have defined as providing intangible assistance to known terrorist organizations, is not covered by free speech protections.

In April, federal authorities arrested Thomas after intercepting messages she was supposedly sending to people connected to ISIS.

She went by "YoungLioness" on Twitter, prosecutors say, and had applied for a visa to travel to Turkey, a common transit point for individuals trying to slip over the border to Syria.

Then FBI agents discovered Thomas bought a ticket to Barcelona and researched ways to move from Spain to Turkey.

But it's her Twitter activity, both public and private messages, that set off alarm bells among federal investigators.

In 2013, Thomas told an overseas ISIS fighter that "would be amazing" to die fighting for ISIS in attacks known as "martyrdom operations," according to investigators.

Prosecutors say in another message she tweeted a photo of a young male child wearing firearm magazine pouches and camouflage with the caption: "Ask yourselves, while this young man is holding magazines for the Islamic state, what are you doing for it? #ISIS."

She also tweeted that "I wouldn't be pleased till I become a solider of the Islamic State."

In addition to wanting to become a martyr herself, she wanted to marry a jihad fighter, according to federal charging documents.

In the motion to dismiss, Thomas' defense attorney said, "Marriage to a militant fighter, without more, is not illegal in itself."

But the judge sided with prosecutors that none of her actions should be considered in isolation, but rather part of a broader quest to join and fight for the Islamic State group.

Thomas' defense attorney Kathleen Gaughan argued in court filings that Thomas has the right to speak freely on any topic and "associate with others for the purpose exercising her religion freely."

"Regardless of the generally held view of ISIS, or how repugnant its tactics are perceived to be, Ms. Thomas's activities and beliefs are protected by the First Amendment," she wrote.

Case law, however, doesn't support that argument, said Judge Baylson. In particular, the U.S. Supreme Court held in Holder v. Humanitarian Law Project that government can prosecute someone for providing material support to terrorists without violating the defendant's free speech.

Thomas is among more than 70 defendants who have been charged with ISIS-related activity stemming from social media communication, according to terrorism expert Seamus Hughes with George Washington University's Center for Cyber and Homeland Security.

"I think there's a realization, both in the Department of Justice and the FBI, that they have to be more forward-leaning when it comes to cases," Hughes said. "So, in the past, they let things develop a little more, but after recent homegrown attacks, they're essentially moving the bar a little bit farther."

At her first court hearing in April, Thomas wore a burqa and said "yes" when asked if she understood the charges.

Thomas' trial date is set for June. If convicted, she could face up to 15 years behind bars.

The FBI has said it is currently looking into more than 900 people in the U.S. for possible links to ISIS.

"That means 900 people have social media accounts. And 900 people you have to follow on a regular basis," Hughes said. "And that's when you have to triage the system, and figure out who's the real threat and who's not."