ONE evening in late September John Perkins, a veteran of the civil-rights movement, attended a rally at a Baptist church in Jackson in support of what he called “a total justice issue”. But this aspect of justice had nothing to do with any of the issues ordinarily associated with the civil-rights movement. It was concerned with Amendment 26, a measure on Mississippi's ballot this November that defines a person as being “every human being from the moment of fertilisation, cloning or the functional equivalent thereof”.

The reason for the measure is straightforward; its consequences less so. The Supreme Court, in its landmark Roe v Wade ruling in 1973, held that the right of a woman to terminate her pregnancy in the first trimester was guaranteed by her constitutional right to privacy. But Harry Blackmun, the liberal justice who wrote the court's majority opinion, noted that Henry Wade, the defendant, and others “argue that the fetus is a ‘person' within the language and meaning of the Fourteenth Amendment…If this suggestion of personhood is established, [Jane Roe's] case, of course, collapses, for the fetus's right to life would be guaranteed specifically by the amendment.” In Blackmun's view the constitution and judicial precedent failed to establish that personhood applied to the unborn. Mississippi is trying to fix that.

The measure is expected to pass. Mississippi is a conservative, religious state, and Brad Prewitt, the executive director of Personhood Mississippi, said that for most Mississippians, “this is a biblical issue.” The state already has a “trigger law” on the books, which would ban most abortions should the Supreme Court overturn Roe v Wade. And abortion providers in the state have to perform ultrasounds on all patients, giving them the chance to see the image before the procedure. Both the Republican and Democratic candidates for governor support the personhood measure, as does the attorney-general.

But what happens once the measure passes is unclear. Roe v Wade's guarantee of first-trimester abortions remains in effect, and the constitution's supremacy clause ensures that when state and federal laws are in conflict, federal law wins. So abortions would not immediately become illegal. But supporters are playing a longer game. Planned Parenthood and the ACLU sued (unsuccessfully) to prevent Amendment 26 from appearing on the ballot. If they sue once it becomes law, a series of lawsuits and appeals may well lead to the Supreme Court, whose political composition is far more favourable to anti-abortion activists than it was in 1973.

And there are other consequences that do not enjoy the same constitutional protection as abortion. Cloning and embryonic stem-cell research would be banned in Mississippi, as could the “morning-after pill” and IUDs. Personhood supporters say the measure would not ban in-vitro fertilisation, but neither would it permit unused embryos to be destroyed. Precisely what doctors are supposed to do with these embryos is unclear.

Then there are unexpected issues. Would embryos be counted as people for the purposes of a census? Could a pregnant woman be charged with child abuse if she smokes, or be denied chemotherapy if it might hurt the fetus? From Mississippi's tiny unborn people come strange legal questions.