FIRST ON FOX: More than a dozen state attorneys general sent a letter to public university and college presidents in their respective states Thursday warning them against invoking the assassination of Charlie Kirk to chill conservative free speech, or face investigations and potential lawsuits, Fox News Digital exclusively learned."Unfortunately, we have heard troubling reports that some university officials are using the murder of Charlie Kirk as a justification to shut down speech on campus," the letter reads. "While considering safety concerns, it is critical that universities are not imposing what would effectively be a tax on free speech.""Particularly at this moment, when free speech itself was attacked, our universities must show through their actions that they will defend free speech and resist the Assassins Veto.' You have an obligation to protect free speechyou must not use the burden of protecting free speech to prevent free speech."The "assassins veto" is understood as a phenomenon of using violence or threats of violence to silence opposing views.CHARLIE KIRK'S KILLING AT UTAH UNIVERSITY PROMPTS SCRUTINY OF SECURITY MEASURESAt the heart of the letter is the issue of security costs as it pertains to conservative speakers. Colleges and universities previously have come under fire over accusations of charging higher security fees for conservative speakers.Such accusations have led to free speech lawsuits in the past, including the University of California, Berekely, settling a lawsuit with campus conservative groups, the College Republicans and Young America's Foundation, in 2018 concerning allegations the school discriminated against conservative speakers by leveling higher security fees and other safety restrictions that led to the cancellation of right-leaning speakers on campus.Berkeley argued that the higher security fees were based on assessment from law enforcement officials that the speakers were likely to face an increase in public disruption and violence, before reaffirming its "commitment to free speech" and changing its security fee operations.The state attorneys general called on colleges to ensure they "impose security fees in a content-neutral and viewpoint-neutral manner" or face potential investigation and legal action.YEARS OF CAMPUS ATTACKS ON CONSERVATIVE ACTIVISTS RESURFACE AFTER CHARLIE KIRKS MURDER"Any security policy that appears neutral on its face must not be applied in a discriminatory manner. There is a long and troubling trend of universities misusing security policies to unconstitutionally chill conservative speech on campus. For example, just last year, the U.S. District Court for the District of New Mexico issued a preliminary injunction against the University of New Mexico after the university attempted to charge Turning Point USA over $5,000 in security fees for an October 2023 event featuring conservative speaker Riley Gaines. As the Court found, that was unacceptable," the letter continued, pointing to another instance of colleges using security fees to allegedly silence conservative voices.The letter was spearheaded by Republican Iowa Attorney General Brenna Bird. A total of 17 Republican state attorneys general signed onto the letter, including top law enforcement officials from Alabama, Alaska, Arkansas, Florida, Georgia, Indiana, Kansas, Louisiana, Missouri, Montana, Nebraska, Oklahoma, South Carolina, South Dakota, Texas and Utah."The tragedy of Charlie Kirks assassination is a sobering reminder that the right to free speech must be protected," Bird told Fox Digital. "Charlie was murdered while debating on a university campus, a place where the free exchange of ideas should be encouraged; we cannot allow the actions of an assassin to stop free speech in any way. Colleges and universities must take steps to keep their students safe while preserving free discussion and open debate."Kirk was killed Sept. 10 while he was at Utah Valley University's campus as part of a Turning Point USA event. The conservative powerhouse was sitting under a tent while chatting with students when a single shot rang out and struck Kirk in the neck."We were shocked and saddened by the assassination of Charlie Kirk on the campus of Utah Valley University on Wednesday," the letter reads. "As the chief law enforcement officers of our states, we unequivocally condemn political violence of any kind. The fact that the slaying took place on a college campus, during a debate, makes it even more tragic.""It is critical our state institutions of higher learning serve as forums for robust debate from all perspectives," the letter continued. "The campus should be the very place where the First Amendment rings loudest for all to hear. We urge you to say no to the 'Assassins Veto.'"The attorneys general argued that students might be considered "consumers" under the respective states' Consumer Fraud Acts or Unfair and Deceptive Acts and Practices laws, and that the universities might violate state "laws if you invoke security concerns to impose exorbitant fees on student groups," while simultaneously advertising to students that the school is open for discussion and dialogue across the political spectrum.CHARLIE KIRK ASSASSINATION: TIMELINE OF UTAH CAMPUS SHOOTING DETAILS ATTACK, MANHUNT FOR SUSPECT"If we receive complaints about your school, we will fully and fairly investigate those complaints subject to the authority of our respective offices," the state attorneys general wrote. "Our offices are committed to ensuring that all our state entities, including our public colleges and universities, follow the Constitution."Conservative nonprofits, including President of Defending Education Nicole Neily, celebrated that the AGs' calls for better protecting free speech is the ideal way to honor Kirk's legacy."This is a moment for leadership, and we are deeply grateful that the nation's attorneys general are using their authority to remind university administrators of their sacred obligation to protect free speech and open discourse on college campuses," she said. "I can think of no better way to honor Charlie's legacy than through ensuring that students voices cannot be silenced by fear or malice."Will Hild, the executive director for Consumers' Research, a longtime nonprofit dedicated to consumer information, lauded Bird for leading the charge on ending the "assassin's veto.""By sustaining the assassin's veto, these University bureaucrats are actively aiding Charlie's murderer, using the threat of violence to cut off free debate," Hild told Fox Digital. "Such a practice is not just antithetical to everything Charlie Kirk represented but to the very principles of America. Attorney General Birds leadership in rallying states' top law enforcement officers to oppose the Assassins Veto in all its forms is encouraging and should be emulated by others. Last weeks atrocity should be a turning point for every American campus."Kirk's funeral is scheduled for Sunday in Arizona and is expected to be attended by President Donald Trump and other administration leaders.