Several states have created person-hood laws, and others are trying. They are in effect an end-run against the SCOTUS ruling legalizing abortion. Declare someone to be a 'person' and you can charge anyone that kills them with murder, as opposed to abortion.
First let me congratulate the creators for a well thought out plan. The question is, why didn't they do this in the first place? Instead of making abortion illegal, just charge the doctor with murder? Because if you don't believe the embryo is a person, then abortion should be legal, and the defense just have to prove reasonable doubt.
There only reason they has specific 'anti-abortion' laws was the problem in convincing a jury that an embryo was a person. They originally solved it by making specific laws against abortion, as opposed to declaring them a person. Person-hood laws seems on the face to be a superior solution.
But sorry, these laws are unconstitutional.
You see, if the individual states have the legal authority to declare someone a person, than by definition they also have the legal right to declare someone NOT a person and that they therefore do not have any rights. If you can make it illegal to kill someone by declaring them a person, then the same state could also make it legal to to kill someone by declaring them not a person.
We fought a civil war over this issue. A bunch of racists declared slaves to not be people - in fact they declared them to be three fifths of a person, as per Article I, Section 2. of the original Constitution, at least for census purposes.
But let's ignore this glaring problem.
So, what US constitutional laws prevent the states from declaring someone a person - and by definition, declaring someone not a person.
Well, The 14th Amendment (passed July 9th, 1868 - just after the Civil War) says:
"All persons born or naturalized in the United States and subject to the
jurisdiction thereof, are citizens of the United States and of the State wherein
they reside. No State shall make or enforce any law which shall abridge the
privileges or immunities of citizens of the United States; nor shall any State
deprive any person of life, liberty, or property, without due process of law;
nor deny to any person within its jurisdiction the equal protection of the laws."
This declares who is a citizen and not a citizen, with the word 'person' a key part of the definition. You need to have been born or naturalized. The unborn don't qualify and can't qualify as a citizen. They clearly are not citizens and have not rights. But perhaps you could argue that it lets the states decide what the word 'person' means. But you see, lawyers have tried this trick before. Hell, even Bill Clinton tried it ("It depends on the meaning of the word 'is'.") Judges are wise to this trick.
The states can't deny these rights to any person. This also means they can't give those privileges. The state of New York can't suddenly declare some random immigrant to be a citizen,
the constitution reserves that power to the federal government.
Let's say I am wrong. Say the states can decide who is and who is not a person. Then the State of Montana could declare all cows people. Montana has 967,440 human and over 2.6 million cattle. Suddenly, Montana has tripled it's population. The cows were born in the US, so by the constition, they become citizens. Obviously Montana declares them wards of the state and unable to vote. But the state can insists on getting 3x the number of congressman and 3x the number of electoral votes. Not to mention Federal money, including Medicaid, unemployment, welfare, etc. all for the benefit of their new 'persons'.
What, cows too ridiculous? What about living cell samples taken from a live human? Can the state culture 2,000,000 of them and declare each one a person? No. Not even if the cells are surgically removed from the womb of a willing woman (technically 'born').
It is fairly obvious why the states can not do this. It is unconstitutional for the states to define legal language. They can suggest, they can offer advice, but the judges decide what the words mean.
Article II, Section of the US Constitution gives the Supreme Court Judges the right to interpret the Constitution, NOT the states. It says "The judicial Power shall extend to all Cases, in Law and Equity, arising under
this Constitution, the Laws of the United States, and Treaties made, or which
shall be made, under their Authority;..."
Judges, not the states, determine the meaning of words for legal purposes. The states can't override the judges decisions. The states legislature can try to influence them, but the can not change the legal definition of words that are important to the Constitution. They can't declare women to be cattle, they can't declare cattle to be people, and they can;t declare unborn embryos to be people. Which means the states can not decide who is and is not a person. Because if they could, they could declare cows (or horses, or pigs, etc) to be people, thus granting them right to be counted under the Census, giving a state too many electoral votes.
The only way to get a legal person-hood bill into law is to over-ride the Supreme Court. That takes an Amendment to the United States Constitution, nothing less.