Justice Samuel Alito raised concerns about a "potentially significant loophole" in the Supreme Court's decision to curb universal injunctions, and now his warning is hanging over lawsuits involving President Donald Trump.Alito said in his concurring opinion in Trump v. CASA that class action lawsuits and lawsuits brought by states leave room for judges to hand down injunctions that, in practice, would function the same way a universal injunction does."Federal courts should thus be vigilant against such potential abuses of these tools," Alito said.SCOTUS RULES ON BIRTHRIGHT CITIZENSHIP ORDER, TESTING LOWER COURT POWERSAlito's warning comes as judges continue to hand down sweeping rulings and as plaintiffs begin filing lawsuits tailored to avoid running into the new roadblock established by the high court.In one major ruling, Judge Randolph Moss, an Obama appointee based in Washington, D.C., found this week that Trump's proclamation declaring an "invasion" at the border was unlawful.Trump's proclamation restricted migrants from claiming asylum when crossing into the United States, a practice the Trump administration says has been abused by border crossers.Moss "set aside" that policy under the Administrative Procedure Act, which had an effect similar to that of a nationwide injunction. More than a dozen potential asylees brought the lawsuit, and Moss also agreed to certify the case as a class action lawsuit that applied to all potential asylees in the country.The Trump administration immediately appealed the ruling. Attorney General Pam Bondi said in a statement that Moss was a "rogue district court judge" who was "already trying to circumvent the Supreme Courts recent ruling against nationwide injunctions."TRUMP CELEBRATES SUPREME COURT LIMITS ON 'COLOSSAL ABUSE OF POWER' BY FEDERAL JUDGESIn his concurring opinion, Alito warned against class action lawsuits that do not strictly abide by Rule 23, which lays out the criteria for certifying a class. He said the Supreme Court's decision on universal injunctions will have "very little value" if district courts do not adhere to the rule."District courts should not view todays decision as an invitation to certify nationwide classes without scrupulous adherence to the rigors of Rule 23," Alito wrote. "Otherwise, the universal injunction will return from the grave under the guise of nationwide class relief, and todays decision will be of little more than minor academic interest."Alito also noted that another area for exploitation could be states that seek statewide relief from a court.For instance, Democrat-led states have filed several lawsuits challenging Trump's policies. A judge could grant those states statewide injunctions, meaning everyone living in the state would be exempt from the policies. Alito warned that giving third parties widespread standing in cases in that manner required careful scrutiny.If judges are lax about these statewide lawsuits, states will have "every incentive to bring third-party suits on behalf of their residents to obtain a broader scope of equitable relief than any individual resident could procure in his own suit," Alito wrote. "Left unchecked, the practice of reflexive state third-party standing will undermine todays decision as a practical matter."