By a 7-2 majority, justices reinforced a 2000 ruling that said they cannot rule on the constitutionality of measures until voters or the Legislature have had a chance to pass them.
A Hinds County judge earlier rejected opponents' arguments against the two amendments without addressing the constitutional issues they raised.
Opponents of the personhood amendment said supporters were using the initiative process to change the state constitution's Bill of Rights. However, amendment supporters said they were trying to define "person" as it is used in the Bill of Rights, not make changes to it.
The proposed eminent domain constitutional amendment would prohibit state and local government from taking private land to give to another person or business.
A voter ID initiative also will be on the November ballot.