Can First Cousins Marry In Illinois? (Explained)

It is illegal for first cousins to marry in Illinois with some exceptions.

If the couple are both 50 or over, there is no impediment. If either is below 50 then they must produce evidence that one of the couple is infertile.

More distant cousin relationships are allowed to marry.

This article reviews the important aspects of cousin marriage within the Prairie State.

What Do The Illinois Marriage Laws Say About First Cousins?

The Illinois marriage laws have a short statement about the type of cousin that cannot marry in the state:

a marriage between cousins of the first degree;

Illinois marriage laws

We’ll examine the exceptions in the next section. But first, let’s clarify what “cousins of the first degree” means.

It may seem obvious that this means first cousins. But read on to be sure.

Unusual terminology

Unfortunately, the Illinois legislators decided to use terminology that differs from other states and from how genealogy describes relationships.

In a family tree, a relative of the first degree is a parent, child, or sibling. A first cousin is actually a third degree relative.

However, we can say that Illinois means “first cousins” by this description.

First cousins once removed can marry

The children of your first cousins are your first cousins once removed. So, where do they stand in Illinois?

The Illinois laws are more ambiguous than some other states. However, court rulings have provided clarification.

The Illinois Supreme Court handed down a ruling in 1959 when a will was contested on the grounds that the married couple were first cousins once removed.

The court decided that this relationship was not cousins of the first degree.

What about half cousins?

Half cousins are where the parents involved in the cousin relationship are half siblings.

Well, it’s not at all clear to us what Illinois intends in this situation.

The laws are clear that half siblings themselves can’t marry. But are their children related within one degree – in the minds of the Illinois legislators? We can’t tell.

Exceptions To The Marriage Laws

Here is the clause that describes the exceptions:

(i) both parties are 50 years of age or older; or

(ii) either party, at the time of application for a marriage license, presents for filing with the county clerk of the county in which the marriage is to be solemnized, a certificate signed by a licensed physician stating that the party to the proposed marriage is permanently and irreversibly sterile;

Illinois marriage laws

Quick explanation

If you’re scratching your head over the wording, then this is what the laws mean:

If you are both aged fifty or older, then you can get married with no extra obstacles.

If either is under fifty, then you need proof that one member of the couple is infertile.

What’s behind these exceptions?

Other states have a moral objection to first cousin marriage, full stop.

Illinois is clearly basing its objections on the potential health risks to children. I won’t get into the pros and cons of this argument.

However, I do think that the laws are better phrased than similar efforts in Arizona where they just mention providing proof of infertility to a judge.

In contrast, Illinois spells out that you need a certificate from a doctor. We hope that women who are post-menopause will have little difficulty or extra expense in getting this document.

The burden of proof may be more complicated when the man has to prove infertility. This may require a more expensive medical examination. However, this will depend on the medical history of the individuals involved.

Types Of Cousins That Can Get Married In Illinois

Marriages between second cousins are allowed. Of course, more distant cousins are also permitted.

If you’re not sure what the difference is between the various relationships, the links below will give you diagrams and clear explanations.

Does The Illinois Marriage Application Form Ask If You’re Related?

We reviewed the online application form for a marriage license from Dupage County in 2022.

The form asks you to describe how you are related to your fiance.

If you are a second cousin, you will still answer yes to the main question (are the parties related).

Be prepared to be asked to clarify by the official who is issuing the marriage license. Don’t worry! Just explain clearly how you are more distant than a first cousin relationship.

Do Nearby States Allow First Cousins To Marry?

Illinois is bordered by Indiana, Iowa, Kentucky, Missouri, and Wisconsin. None of these states allow marriage between first cousins.

The nearest option is probably down south to the Volunteer State. You can check out our article on first cousins marrying in Tennessee.

Illinois Neighbors

Looking for a destination wedding spot?

Do you live in a state or country where first cousin marriage is legal and you simply wanted to visit Illinois as a destination wedding spot?

You could split your vacation between Illinois and a ceremony in Tennessee!

Looking to relocate?

Some first cousin couples move lock, stock, and barrel to another state where their marriage will be legal.

Review your options and future plans carefully. You may wish to sit down with an attorney.

If you intend to move from place to place through your lives, be aware that some states in the U.S. will not recognize legal marriages from other states.

Roman Catholic Marriages

Even if close cousins move to another state that allows their civil marriage, they will face separate hurdles if they want a wedding in a Roman Catholic church.

Historically, the Catholic Church hasn’t encouraged first cousin marriages. However, the church laws have been relaxed somewhat in recent years.

There is a process that first cousins need to go through with the hierarchy in order to get permission to marry in a church ceremony. This is known as a dispensation.

You can read a more detailed explanation here on how first cousins can have a Catholic wedding.

What about other cousins?

Second cousins (and further out) don’t need to get special permission for a Catholic Church marriage.

We suggest that you mention to your priest that you are second cousins before the service. This means he won’t get uneasy if he hears mention of “cousins” from other people.

If you’re not sure about whether you are first or second cousins, check out our article on what second cousins are.

Frequently Asked Questions

Here are some quick answers to common questions.

Does Illinois allow relatives to marry?

Illinois does not allow close relatives to marry.

More distant relatives such as second cousins are allowed to marry in the state.

Can you marry a sibling in Illinois?

Illinois does not allow siblings to marry. Half-siblings are also not allowed to marry in the state.

Is it legal to marry your second cousin in Illinois?

Marriage between second cousins is legal in Illinois.


The codes and laws referenced in this article may not be the most recent version. Illinois may have more current or accurate information.

We make no warranties or guarantees about the accuracy, completeness, or adequacy of the information contained on this site or the information linked to on other sites. Please check official sources.

Margaret created a family tree on a genealogy website in 2012. She purchased her first DNA kit in 2017. She created this website to share insights and how-to guides on DNA, genealogy, and family research.

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