California Adultery Laws: Is It Illegal to Cheat on Your Spouse?

The discovery of infidelity is a deeply painful and disruptive moment in any marriage. Amid the emotional turmoil, practical and legal questions quickly surface. One of the most common, often asked in a state of shock and anger, is: “Is what they did illegal?” In a state as populous and culturally significant as California, the answer has profound implications for millions.

If you’re navigating this difficult situation, you might envision a courtroom drama where the unfaithful spouse is punished by a judge. But the legal reality in the Golden State is far different from what you see on television.

The short answer is straightforward: No, adultery is not illegal in California. It is not a crime. You cannot have your spouse arrested, and they will not face criminal charges or jail time for infidelity.

However, this simple “no” doesn’t tell the whole story. While adultery itself isn’t a crime, the actions surrounding it can have significant and specific consequences within a California divorce proceeding. Understanding these nuances is crucial for anyone facing the end of a marriage due to an affair. This article will walk you through the historical context, the modern legal landscape, and the precise ways infidelity can—and cannot—impact your divorce.

Is Adultery a Crime in California?

Unlike states such as Michigan, where adultery could technically fall under criminal jurisdiction, California law makes a clear distinction. The California Penal Code does not list adultery as a crime, and individuals cannot be arrested or prosecuted for being unfaithful to their spouse.

This is an important point because many people assume infidelity falls under criminal law due to religious or moral teachings. In reality, California approaches adultery as a personal matter rather than a crime against the state.

Adultery and Divorce Proceedings in California

Where adultery does become relevant is in the realm of divorce law. California is a “no-fault” divorce state, which means either spouse can file for divorce citing “irreconcilable differences” without proving infidelity, abuse, or other wrongdoing.

The Shift to ‘No-Fault’ Divorce: A California Revolution

To understand why adultery isn’t a crime today, we have to look back in time. For decades, California, like most other states, operated under a “fault-based” divorce system. In this system, the person filing for divorce had to prove that their spouse was guilty of a specific wrongdoing, such as cruelty, abandonment, or, most famously, adultery.

These fault-based divorces were often messy, public, and punitive. They required spouses to hire private investigators, gather salacious evidence, and air their private grievances in open court. A high-profile divorce in Los Angeles could become front-page news, with private details of an affair becoming public fodder. The system was seen as archaic, encouraging conflict and fabrication rather than resolution.

In 1969, under then-Governor Ronald Reagan, California became the first state in the nation to radically change this system by signing the Family Law Act. When it took effect on January 1, 1970, it ushered in the era of “no-fault” divorce. This was a monumental legal shift.

Under the new law, a person no longer had to prove fault. Instead, a divorce could be granted based on “irreconcilable differences,” essentially meaning the marriage had irretrievably broken down and there was no reasonable chance of getting back together. This revolutionary concept aimed to reduce the acrimony and emotional damage of divorce proceedings, allowing couples to dissolve their marriage with more dignity and less public mudslinging. By removing the need to prove wrongdoing like adultery, the state also effectively decriminalized it in the context of ending a marriage.

If It’s Not a Crime, Does It Matter at All in a Divorce?

This is the most critical question for anyone going through this experience. Just because adultery isn’t a basis for divorce doesn’t mean it’s legally irrelevant. The conduct of an affair can intersect with the three main pillars of a divorce case: property division, spousal support, and child custody.

Impact on Division of Marital Property

California is a community property state. This is a foundational concept in any California divorce. It means that, with few exceptions, any assets or debts acquired during the marriage—from the day you say “I do” until the date you officially separate—belong equally to both spouses. This includes income, real estate, investments, and retirement accounts.

The default rule is an equal 50/50 split of all community property. Your spouse’s infidelity does not entitle you to a larger share. A judge in San Diego or San Francisco cannot award you 70% of the assets simply to punish your spouse for cheating. The law is designed to be equitable, not punitive.

However, there is a major exception where adultery becomes highly relevant: the misuse of community funds.

If the unfaithful spouse used marital money to finance their affair, that money is considered a “breach of fiduciary duty.” Spouses have a legal duty to act in each other’s best financial interests. Using joint funds on a third party without the other spouse’s consent is a clear violation of this duty.

Consider these scenarios:

A spouse in Silicon Valley uses a joint savings account to buy expensive jewelry and designer clothes for their affair partner.
A partner in Orange County pays for lavish vacations to Hawaii, international flights, and five-star hotels with their lover using a community credit card.
Someone secretly pays the rent on an apartment in Santa Monica for their affair partner for over a year using funds from their paycheck, which is community property.*

In these cases, the innocent spouse can bring this spending to the court’s attention. A judge has the authority to rectify this financial misconduct. They can order a reimbursement, essentially giving the innocent spouse a larger share of the remaining assets to make up for the money that was improperly spent.

To do this, you will need proof. This is where bank statements, credit card bills, and other financial records become invaluable evidence.

Impact on Spousal Support (Alimony)

Spousal support, often called alimony, is designed to help a lower-earning spouse maintain the standard of living established during the marriage for a certain period. The calculation is complex, and a judge considers numerous factors listed in California’s Family Code, such as the length of the marriage, the earning capacity of each spouse, and their age and health.

Is adultery one of those factors? Officially, no. A judge cannot increase the amount or duration of spousal support to punish a cheating spouse or decrease it because the recipient had an affair. The calculation is meant to be based on financial need and ability to pay.

However, there are subtle, indirect ways an affair can play a role. For instance, if a spouse’s new relationship affects their financial situation, it can become relevant. If a spouse who would otherwise be requesting support moves in with a new, wealthy partner, their need for support may be reduced or eliminated. Conversely, if a paying spouse quits a high-paying job in Sacramento to move to a rural area with their new partner and takes a much lower-paying job, the court may view this as a voluntary underemployment and “impute” income to them, meaning they calculate support based on what they should be earning.

While the law lists the “moral character” of the parties as a potential consideration, judges in California almost never use this vague factor to adjust support based on simple adultery. The conduct would have to be exceptionally egregious and directly tied to financial harm to even be considered.

Impact on Child Custody and Visitation

For parents, nothing is more important than their children. A common fear is that a judge will view the unfaithful parent as morally unfit and deny them custody.

This fear is largely unfounded. California family courts operate under a single, guiding principle: the best interests of the child. A judge’s decision on custody and visitation will be based entirely on what arrangement best serves a child’s health, safety, and welfare.

A parent’s affair, in and of itself, does not make them an unfit parent in the eyes of the law. A judge will not strip a mother or father of custody simply because they were unfaithful to their spouse. The court assumes that it is in the child’s best interest to have a strong and continuing relationship with both parents.

However, as with other areas, the conduct surrounding the affair can become a critical factor if it negatively impacts the children. The focus shifts from the act of infidelity to its effect on the children’s well-being.

Here are situations where an affair could influence custody decisions:

Exposing children to inappropriate situations: If a parent brings their new partner around the children immediately after separation, causing confusion and emotional distress, or engages in inappropriate behavior in front of them.
Neglecting parental duties: If a parent is so consumed by their new relationship that they miss visitation times, forget to pick up the children from school, or otherwise fail to meet the children’s needs.
The character of the new partner: If the new partner has a history of substance abuse, domestic violence, or criminal activity, a judge would be deeply concerned about exposing the children to that person.
Parental alienation: If the parent who had the affair speaks badly about the other parent to the children, attempting to damage their relationship.

In these instances, the court isn’t punishing the adultery; it is protecting the children from harm, instability, and emotional distress.

Beyond Divorce Court: Other Potential Legal Tangents

While the main impact of adultery is felt within a divorce case, there are a few other legal areas where it can appear.

Defining the Date of Separation: This is a crucial date in a California divorce, as it marks the end of the community property period. Anything earned or acquired after this date is separate property. An affair can often provide a clear, factual event that helps the court pinpoint the exact date the marriage ended, which can have significant financial consequences.
Military Law: This is a key exception to be aware of. While adultery is not a civilian crime in California, it is still a criminal offense under the Uniform Code of Military Justice (UCMJ). A service member stationed at Camp Pendleton or Naval Base San Diego could face non-judicial punishment or even a court-martial for adultery if the conduct is deemed to bring discredit to the armed forces.
“Heart Balm” Torts: In the past, you could sue your spouse’s lover for “alienation of affection” or “criminal conversation.” These lawsuits, known as “heart balm” torts, have been abolished in California. You cannot sue the third party for damages related to the affair.*

To summarize the key takeaways:

Adultery is not a crime in California.
It is not a legal reason for a “no-fault” divorce.
It does not affect the 50/50 division of community property, unless marital funds were wasted on the affair.
It generally does not impact spousal support calculations.
It does not determine child custody, unless the behavior associated with the affair endangers the children’s well-being.

Navigating a divorce is one of life’s most challenging experiences, and infidelity adds another layer of pain and complexity. While the law may not offer the moral vindication you seek, it provides a structured path for separating your lives fairly. The most important step you can take is to seek guidance from an experienced California family law attorney. They can help you understand your rights, protect your financial interests, and advocate for the best interests of your children, allowing you to move forward with clarity and confidence.

Disclaimer: This article is intended for general informational purposes only and does not constitute legal advice. Laws and ordinances can vary by city, county, and state, and they may change over time. If you have specific questions about your situation or obligations under law, you should consult with a licensed attorney or contact your local municipal authority for guidance.