Yes, you can subpoena your husband’s girlfriend in a divorce if she has information relevant to a contested issue in the case. A subpoena is a court order that compels a non-party to appear and testify, produce documents, or both, and the girlfriend is not shielded from that process simply because she isn’t married to either of you. The question that actually decides whether a judge will enforce it is narrower: does she hold evidence that bears on your finances, on support, or on your children’s welfare?
When a Subpoena Against Her Will Actually Help
Courts will not enforce a subpoena because you are angry about the affair. The information has to connect to something the judge is being asked to decide. Three situations usually clear that bar.
Dissipation of Marital Assets
This is the strongest reason. Dissipation happens when one spouse spends marital money for a nonmarital purpose while the marriage is breaking down. Gifts, rent payments, vacations, and direct transfers to a girlfriend all qualify. Courts have found dissipation where a husband bought expensive recreational items that primarily benefited a girlfriend and the spending fell outside the couple’s normal standard of living. If you believe marital funds went to her, her bank statements, gift receipts, and testimony about what she received can help you recover your share in the property division.
Alimony and Cohabitation
In many states, if a spouse receiving alimony begins living with a new partner in a marriage-like relationship, the paying spouse can ask the court to cut or end payments. The reverse matters too. If your husband is claiming financial hardship to reduce what he owes you while quietly supporting a girlfriend, records of shared bills, joint accounts, or rent payments show the court his real financial picture. A subpoena to the girlfriend can produce those records.
Child Custody
Where the girlfriend will spend regular time around your children, the court’s duty to protect their best interests opens the door to discovery about her background and conduct. The subpoena still has to be targeted. Evidence of substance abuse, criminal history, or conduct that creates an unsafe environment is fair game. A broader inquiry driven by jealousy rather than genuine concern for the children will get shut down quickly.
No-Fault Divorce and What It Changes
Before you spend money chasing the girlfriend, understand how your state treats adultery. Every state now offers some form of no-fault divorce, and in purely no-fault jurisdictions, proving the affair itself will not change the outcome of the decree. The affair does not earn you a larger property share or a custody advantage on its own.
Evidence tied to the affair can still matter when it affects money. A judge who will not punish your husband for cheating will absolutely punish him for draining the joint savings to fund it. Keep the focus there. You are not subpoenaing the girlfriend to prove adultery. You are subpoenaing her to show where the money went, whether cohabitation changes support, or whether she poses a risk to your children.
Testimony, Documents, or Both
Subpoenas come in two forms. A subpoena ad testificandum compels the witness to appear and give sworn testimony at a deposition or hearing. A subpoena duces tecum compels her to produce specific documents or other tangible evidence. In most divorce situations involving a girlfriend, you want both. Her records tell part of the story and her testimony fills in the gaps.
Specificity matters when you request documents. Asking for “all financial records” invites a successful challenge. Request bank statements from a particular account over a defined time period, or receipts for specific purchases you believe came from marital funds. The narrower the ask, the harder it is to fight.
How to Issue and Serve the Subpoena
The process runs through the clerk’s office in the court where your divorce is pending. Your attorney can prepare the form, or if you are representing yourself, the clerk can provide the blank. You will need the girlfriend’s full legal name and a current address where she can actually be served. Without a valid address, nothing moves forward.
The form then has to be officially issued. In many jurisdictions the clerk signs and stamps it, which turns it into a binding court order. Under the federal rules and many state equivalents, an attorney admitted in the issuing court can sign and issue a subpoena directly.
Service
The subpoena must be personally hand-delivered by someone at least 18 years old who is not a party to the case, typically a professional process server or a sheriff’s deputy. You cannot serve it yourself. At delivery, the server must also tender a witness fee and mileage. Under federal law the attendance fee is $40 per day, and mileage is reimbursed at $0.725 per mile in 2026.1Office of the Law Revision Counsel. 28 USC 1821 – Per Diem and Mileage Generally2U.S. General Services Administration. Privately Owned Vehicle (POV) Mileage Reimbursement Rates State courts set their own fee schedules in a similar range.
Timing
The subpoena must give the recipient a reasonable amount of time to comply. What counts as reasonable depends on jurisdiction and scope, but a demand for documents within a day or two is almost certain to be quashed.3Legal Information Institute. Federal Rules of Civil Procedure Rule 45 – Subpoena Many local court rules require at least 14 days’ notice for document production. Check the applicable rules and build enough lead time into the compliance date.
If She Lives in Another State
A court’s subpoena power stops at its border. If the girlfriend lives in a different state, you cannot mail her a subpoena from your court. You have to domesticate it, meaning you ask a local court in her state to issue its own subpoena based on yours.
The Uniform Interstate Depositions and Discovery Act has made this routine in most of the country. At least 46 states and the District of Columbia have adopted the UIDDA. You submit your original subpoena to the clerk of court in the county where she lives, and that clerk issues a local subpoena incorporating your terms. The local subpoena is then served under that state’s rules. If she challenges it, the challenge is heard by the court in her state, not yours. The process adds filing fees and time, but it is far simpler than it used to be.
Texts, Messages, and Social Media
Direct messages, texts, and posts can be powerful evidence of shared expenses, lifestyle, or the relationship itself. The rules depend on who holds the data.
You can subpoena the girlfriend directly for messages, posts, and other digital content on her own devices. She is treated like any other witness with records in her possession. The same rule about specificity applies: ask for messages between her and your husband during a defined period, not everything on her phone.
Subpoenaing the platform is a different problem. The federal Stored Communications Act generally prohibits social media companies and email providers from disclosing the content of private communications in response to a civil subpoena.4Office of the Law Revision Counsel. 18 USC 2702 – Voluntary Disclosure of Customer Communications or Records You can get non-content records such as account creation dates, login history, or the identity of an account holder, but the actual messages have to come from the people involved. This is one of the most misunderstood areas of divorce discovery, and plenty of money has been wasted on subpoenas platforms are legally barred from honoring.
How the Girlfriend Can Push Back
Being served does not mean she has to hand over everything. She has several options, and knowing them helps you anticipate the fight.
Comply
The simplest response is full compliance. Many witnesses pick this route because resisting means hiring an attorney, and the cost of resisting often exceeds the cost of cooperating.
Serve Written Objections
She can serve written objections on the party who issued the subpoena. Under the federal rules, objections to document production must be served within 14 days of receiving the subpoena or before the compliance date, whichever comes first.3Legal Information Institute. Federal Rules of Civil Procedure Rule 45 – Subpoena State deadlines vary. Filing objections suspends the obligation to produce, which puts the burden back on you to file a motion to compel and let the judge decide.
Move to Quash
A stronger challenge is a motion to quash, which asks the judge to throw out the subpoena. Common arguments are that the information is not relevant to any issue in the divorce, that the request is unreasonably broad, that the subpoena seeks privileged material, or that service was procedurally defective.5eCFR. 5 CFR 1201.82 – Motions to Quash Subpoenas The court weighs your need against her privacy interests and the burden of compliance. Because she is a third party, judges hold the subpoena to a higher standard than ordinary discovery between spouses. Overly aggressive requests tend to backfire. A judge who sees a narrow request for relevant financial records will enforce it; a judge who sees a sprawling demand for years of personal communications may quash the whole thing as harassment.
Invoke the Fifth Amendment
If answering specific questions could expose her to criminal liability, she can invoke the Fifth Amendment privilege against self-incrimination. The right applies in civil proceedings. She cannot refuse to appear or issue a blanket refusal. The privilege has to be asserted question by question, and the court evaluates each claim. In a divorce context this comes up around conduct like fraud, theft, or drug use.
If She Ignores the Subpoena
A subpoena is a court order, not a suggestion. A witness who ignores a properly served subpoena can be held in contempt, which may result in monetary fines or, in extreme cases, arrest and forced appearance.6National Institute of Justice. Law 101 – Failure to Honor a Subpoena Most judges hold a hearing first so the witness can explain before sanctions are imposed. If the girlfriend wants to avoid compliance, her only workable path is to challenge the subpoena through the proper channels before the deadline runs.