(CNN) A federal judge has temporarily blocked Arkansas' 18-week abortion ban from going into effect on the grounds that it would cause "irreparable" harm to women seeking abortions.

was based on a diagnosis that the fetus has Down syndrome and another law requiring providers to be certified in obstetrics and gynecology. The American Civil Liberties Union and Planned Parenthood The Tuesday ruling also blocks a new law barring providers from performing an abortion if the woman's decision to terminate the pregnancywas based on a diagnosis that the fetus has Down syndrome and another law requiring providers to be certified in obstetrics and gynecology. The American Civil Liberties Union and Planned Parenthood filed a lawsuit in June against Arkansas Attorney General Leslie Rutledge challenging all three measures as unconstitutional.

In the ruling, District Judge Kristine Baker of the Eastern District of Arkansas wrote that the three measures "cause ongoing and imminent irreparable harm to the plaintiffs and their patients," adding that "the harms to women who are unable to obtain abortion care as a result of (the acts) are irreparable."

Baker specifically addressed the 18-week ban, implying that she would ultimately rule in favor of the abortion rights advocates on the grounds that it is unconstitutional. Roe v. Wade, the landmark 1973 Supreme Court ruling, legalized abortion prior to viability, which can occur at about 24 weeks of pregnancy, nationwide.

"The Court concludes that, at this stage of the proceedings and on the record evidence currently before the Court, plaintiffs are likely to prevail on their argument that (the ban) unconstitutionally restricts pre-viability abortions and, therefore, is facially unconstitutional," Baker wrote.

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