DOJ attorneys argued that an injunction "is necessary to protect the constitutional rights of women in Texas and the sovereign interest of the United States in ensuring that its States respect the terms of the national compact."
Earlier this month, the Supreme court ruled on technical grounds that abortion providers had not made a sufficient case against the Texas Heartbeat Act. They made a 5-4 decision declining to block the law's enforcement, but that decision did not rule on the constitutionality of the Heartbeat Act's enforcement. Legal challenges could still make their way to the Supreme Court and potentially get a different result.
Texas's heartbeat act is resistant to normal means of legal challenges because it is enforced via civil lawsuits rather than direct action by Texas officials. Individuals in Texas can file lawsuits against abortionists or those who assist in the abortions of children with detectable heartbeats.