The question you raise involves constitutional considerations related to equal protection under the law. The issue revolves around whether denying opposite-sex couples the ability to enter into a civil union, while allowing same-sex couples that option, violates the constitutional guarantee of equal protection.
In the United States, the Equal Protection Clause of the Fourteenth Amendment to the U.S. Constitution prohibits states from denying any person within its jurisdiction the equal protection of the laws. The U.S. Supreme Court, in cases such as Obergefell v. Hodges (2015), has held that the fundamental right to marry is guaranteed to same-sex couples, striking down state laws that banned same-sex marriage.
In the context of your question, if a state were to offer civil unions as an alternative to marriage but restrict them to same-sex couples, it might raise constitutional concerns. The principle of equal protection suggests that similarly situated individuals should be treated alike by the law. Denying opposite-sex couples the option of a civil union while providing that option to same-sex couples could be seen as discriminatory.
However, legal interpretation and outcomes can be complex, and the specific facts of a case, as well as the legal arguments presented, can influence the outcome. The landscape of constitutional law, especially regarding LGBTQ+ rights, has evolved over time, and judicial decisions have played a significant role in shaping these principles.
If someone were to challenge such a restriction in court, the court would likely assess the constitutional implications and whether there is a rational basis for treating opposite-sex and same-sex couples differently in this context. The outcome could depend on legal arguments presented, evolving societal attitudes, and precedents set by previous court decisions.
It’s important to note that legal questions like these can be complex and may require careful consideration by legal experts and, ultimately, the judicial system to provide a definitive answer.