A Texas court is thwarting Georgia prosecutors’ attempts to compel testimony from Texas witnesses as part of a criminal investigation into former President Donald J. Trump.ATLANTA — Witnesses called to testify in a Georgia criminal investigation into former President Donald J. Trump and his allies have not always come willingly.A number of them have fought their subpoenas in their home-state courts, only to have local judges order them to cooperate. That was the case with Trump-aligned lawyers John Eastman in New Mexico, Jenna Ellis in Colorado and Rudolph W. Giuliani in New York; Mr. Giuliani was also told by an Atlanta judge that he could come “on a train, on a bus or Uber” after his lawyers said a health condition prevented him from flying.But the state of Texas is proving to be an outlier, creating serious headaches for Fani T. Willis, the Fulton County district attorney, who is leading the investigation into efforts by Mr. Trump and others to overturn his 2020 election loss in Georgia.Last month, the Texas Court of Criminal Appeals, the state’s highest criminal court, thwarted Ms. Willis’s effort to force Jacki L. Pick, a Republican lawyer and pundit, to testify in Atlanta, saying that her subpoena had essentially expired. But in a pair of opinions, a majority of the judges on the all-Republican court went further, indicating that they believed the Georgia special grand jury conducting the inquiry may not have the legal standing to compel testimony from Texas witnesses.After the court’s ruling, two other pro-Trump Texans, Sidney Powell and Phil Waldron, did not show up for their scheduled court dates in Atlanta. And while there may be workarounds for Ms. Willis — experts say the Atlanta prosecutors could go to Texas to depose the witnesses — it looks to some Georgia observers like a pattern of Texas Republicans meddling with Georgia when it comes to the fate of Mr. Trump.Fani Willis, the Fulton County district attorney, has subpoenaed prominent lawyers of Mr. Trump, including Rudolph Giuliani, Jenna Ellis, John Eastman and Sidney Powell.Audra Melton for The New York Times“It does seem like there’s a substantial resistance from Texas and Texans to forcing people to cooperate in ways that we haven’t seen from any other jurisdiction,” said Anthony Michael Kreis, a constitutional law professor at Georgia State University in Atlanta.Ken Paxton, the Texas attorney general, has also weighed in, filing an amicus brief late last month along with other Republican attorneys general that supported efforts by Senator Lindsey Graham of South Carolina to avoid testifying in the Atlanta investigation. Mr. Paxton, in a statement accompanying his brief, assailed the investigation for what he said were its “repeated attempts to ignore” the Constitution.Mr. Paxton, who is running for re-election this year despite having been indicted and arrested on criminal securities-fraud charges, has sought to intervene in Georgia before. After the 2020 election, he sued Georgia and three other swing states that Mr. Trump lost, in a far-fetched attempt to get the Supreme Court to delay the certification of their presidential electors.By refusing to compel the three Texas residents to testify in Georgia, the court is breaking with a long tradition of cooperation between states in producing subpoenaed witnesses. All 50 states have versions of what is known as the Uniform Act, which was created in the 1930s to establish a framework for one state to compel testimony from a witness residing in another.Ms. Willis, in a statement, said, “We expect every state to abide by the Constitutional requirement to ensure that full faith and credit is given by them to the laws and proceedings of other states. That requirement includes abiding by the interstate compact to produce witnesses for other states’ judicial proceedings.”Ms. Willis is weighing potential conspiracy and racketeering charges, among others, and is examining the phone call that Mr. Trump made on Jan. 2, 2021, to Brad Raffensperger, the Georgia secretary of state, imploring him to “find” nearly 12,000 votes, or enough to reverse the outcome of the Georgia vote.On Friday, her office filed paperwork seeking to compel testimony from three more witnesses, The Associated Press reported: former House Speaker Newt Gingrich as well as Michael T. Flynn, a former national security adviser, and Eric Herschmann, a lawyer who worked in the Trump White House.Nearly 20 people, including Mr. Giuliani, have already been informed that they are targets of Ms. Willis’s investigation and could face criminal charges. Ms. Pick, a radio host and former lawyer for House Republicans whose husband, Doug Deason, is a prominent Republican donor and Dallas power broker, has also been told she is among the targets of the investigation, according to one of her lawyers, Geoffrey Harper.She played a central role in one of two December 2020 hearings before Georgia lawmakers that were organized by Mr. Giuliani, who advanced a number of falsehoods about the election. During a hearing before the Georgia Senate, Ms. Pick narrated a video feed that showed ballot counting taking place at a downtown Atlanta arena where voting was held.Jacki L. Pick played a central role in one of two December 2020 hearings before Georgia lawmakers that were organized by Mr. Giuliani.Rebecca Wright/Atlanta Journal-Constitution via APAt the hearing, Ms. Pick said the video “goes to” what she called “fraud or misrepresentation,” and the implication of her presentation was that something improper was taking place. She was immediately challenged by Democrats at the hearing. The office of Mr. Raffensperger, a Republican, has also long refuted the idea that anything nefarious took place in the counting of votes at the arena.Mr. Harper said his client had done nothing wrong.“She didn’t suggest there was fraud, she didn’t suggest something untoward had happened,” he said. “She simply said here is a video, here’s what it shows, we’d like to investigate further. Her testimony is the most innocuous thing you’ve ever seen.”Fulton County prosecutors are also seeking the testimony of Ms. Powell, who like Ms. Pick lives in the Dallas area. She is a lawyer and conspiracy theorist who played a high-profile role in efforts to keep Mr. Trump in power. In Georgia, she helped put together a team of Trump allies and consultants who gained access to a wide range of voter data and voting equipment in rural Coffee County; they are currently being investigated by Mr. Raffensperger’s office, as well as the Georgia Bureau of Investigation and Ms. Willis’s office.In an email, Ms. Powell said, “GA has no need to subpoena me. My involvement in GA issues has been significantly misrepresented by the press including your outlet.”She did not answer questions about her legal strategy with respect to Fulton County’s attempt to make her testify, or say whether she had been informed that she is a target of the investigation or merely a witness.Mr. Waldron, a former Army colonel with a background in information warfare, also advanced a number of conspiracy theories after the 2020 election, and he made a virtual appearance at one of the legislative hearings in Georgia. He could not be reached for comment. He lives outside of Austin, Texas, and the district attorney in the county where he lives said he was not aware of any legal challenge to Ms. Willis’s effort to compel Mr. Waldron’s testimony.Phil Waldron, a former Army colonel, made a virtual appearance at a legislative hearing in Georgia after the 2020 election.Aram Roston/ReutersThe body overseeing the Fulton County investigation is known under Georgia law as a special purpose grand jury. It can sit for longer periods than a regular grand jury and has the ability to subpoena targets of the investigation to provide testimony, though it lacks the power to indict. Once a special grand jury issues a report and recommendations, indictments can be sought from a regular grand jury.A majority of judges on the Texas court expressed the view that the Georgia grand jury was not a proper criminal grand jury because it lacks indictment authority, and thus likely lacks standing to compel the appearance of witnesses from Texas.“I am inclined to find such a body is not the kind of grand jury envisioned by the Uniform Act,” wrote Judge Kevin Yeary. “And if I may be wrong about that, I would place the burden to show otherwise on the requesting state.”His view was essentially backed by four other judges on the nine-member court.The question of whether the Fulton County special grand jury is civil or criminal in nature came up in late August, when lawyers for Gov. Brian Kemp, a Republican, unsuccessfully sought to quash a subpoena demanding that he testify. The governor’s lawyers argued that the special grand jury was civil, and that Mr. Kemp would not have to testify in a civil action under the doctrine of sovereign immunity.But in a written order on Aug. 29, Fulton County Superior Court Judge Robert C.I. McBurney rejected the idea that the special grand jury was civil, noting that none of the paperwork establishing the grand jury mentioned that it would be considering civil actions.“That a special purpose grand jury cannot issue an indictment does not diminish the criminal nature of its work or somehow transmogrify that criminal investigation into a civil one,” Judge McBurney wrote. “Police officers, too, lack the authority to indict anyone, but their investigations are plainly criminal.”Ronald Wright, a law professor at Wake Forest University who studies the work of criminal prosecutors, said that the Texas court’s decision, based on its interpretation of the special grand jury’s purpose, appeared unusual. “I haven’t heard anything about one state saying categorically, ‘No we read your statute, that doesn’t apply here, you can’t get this witness,’” he said.The nine members of Texas’ Court of Criminal Appeals are elected and are all Republicans. But they have not always been in sync with Gov. Greg Abbott and Mr. Paxton, both vociferous Trump supporters. Mr. Harper said his reading of Georgia law is that the special grand jury is a civil proceeding. He believes that witnesses living in other states can challenge efforts to compel their testimony, at least if it is in person.“Civil cases can get testimony from out-of-state witnesses, but they have to do it by deposition,” he said. “I believe that if pressed on the issue, it would be a unanimous ruling by the Texas Court of Criminal Appeals that a special grand jury in Georgia cannot subpoena live testimony from witnesses outside of Georgia.” More