"The trimester system was actually the result of a compromise among the Justices. Blackmun’s original idea was that a woman had the right to an abortion without interference from the state until the end of the first trimester. During the first trimester, the abortion decision was left to “the best medical judgment of the pregnant woman’s attending physician.” Afterward states could limit legal abortions to “stated reasonable therapeutic categories”-such as the woman’s physical or mental health-“that are articulated with sufficient clarity” to give physicians fair warning. The idea was that health regulations were unnecessary until the second trimester because first-trimester abortions were as safe for women as carrying the fetus to term. However, Justices William Brennan and Thurgood Marshall objected that the first trimester didn’t give women enough time to discover that they were pregnant, find a doctor, and take the necessary steps to obtain an abortion. Marshall, in particular, was worried about the effect of Blackmun’s rule on poor and minority women. Blackmun agreed that the first trimester was an arbitrary point, and he responded by pushing the cutoff point to the moment of viability. However, Blackmun believed that states should still be able to regulate abortions for health reasons after the first trimester. In effect, this produced three different sets of rules for three different trimesters. Brennan responded that the point of viability was imprecise. The Court did not have to specify a specific cutoff point but should leave that question to “medically informed” legislatures I the first instance. However, Blackmun ignored this suggestion, and the result was Roe’s trimester framework."