How Do You Challenge Paternity in Pennsylvania?

To challenge paternity in Pennsylvania, you file in the Court of Common Pleas, and how hard the case will be depends almost entirely on how paternity was created. A signed Acknowledgment of Paternity can be undone with no explanation inside 60 days; after that, you need clear and convincing evidence of fraud, duress, or a material mistake of fact.¹ If paternity came from the marital presumption, or if you have acted as the child’s parent long enough for the child to rely on that relationship, the courts add further hurdles that a DNA test alone will not clear.

Challenging a Voluntary Acknowledgment of Paternity

The 60-Day Rescission Window

If you signed an AOP and want out, the first question is whether you are still inside the rescission window. Either signer can rescind within 60 days of signing, or before any court or administrative proceeding involving the child begins, whichever comes first.¹ During that window, you do not need to prove anything. You rescind.

The trap is the “proceeding” trigger. A domestic relations conference on child support counts. If you get notice of a support action and your 60 days are not up, the window closes the moment that proceeding begins, not when you thought it would.

After the 60 Days Run Out

Once the rescission period ends, the AOP has the force of a court order. To undo it, you have to file in court and prove one of three things by clear and convincing evidence:¹

Fraud. The mother lied about who the biological father was, or deliberately concealed that another man could be.
Duress. You were threatened, coerced, or placed under extreme pressure to sign.
Material mistake of fact. You genuinely and reasonably believed you were the biological father based on what you knew at the time.

Clear and convincing evidence sits above the usual civil “more likely than not” standard. The court has to find your evidence highly probable and free of serious doubt. Learning later that you might not be the biological father is not automatically a material mistake of fact. You typically need to show a reasonable basis for your original belief and new evidence that undermines it. A DNA exclusion helps, but the court still has to be persuaded that the original signing came from a real factual error, not indifference or willful avoidance.

One practical warning: an existing child support order stays in effect while your challenge is pending unless the court finds good cause to suspend it.¹ Do not stop paying. Arrears may survive even a successful outcome.

Rebutting the Marital Presumption

When a child is born during a marriage, Pennsylvania presumes the husband is the father. That presumption is deliberately hard to overcome. Under a 2025 Pennsylvania Supreme Court decision, to rebut the marital presumption and obtain DNA testing you must show by clear and convincing evidence that there is a reasonable possibility you are the father, and that resolving the question through genetic testing serves the best interests of the child.²

The best-interests piece is where these cases turn. The court is not asking whether biological truth would be nice to know. It weighs the child’s age, the length and quality of the existing parent-child relationship, the potential harm from disrupting that relationship, and the circumstances under which the biological question came up.² A challenger who suspected the issue years ago and waited will fare worse than one who raised it promptly.

Paternity by Estoppel

Even with a DNA exclusion in hand, Pennsylvania courts can block a challenge entirely through paternity by estoppel. It is the obstacle people most often underestimate.

The idea: if a man has held himself out as the child’s father, built a parent-child bond, and the child has come to rely on that relationship, the court can find that severing the legal tie would harm the child. At that point, the man is legally barred from denying paternity no matter what a test shows. The doctrine sits alongside the marital presumption as one of Pennsylvania’s two common-law pillars of paternity law.²

Estoppel is decided case by case, with the child’s best interests as the governing principle. Conduct that tends to trigger it includes being named on the birth certificate, providing regular financial support, living with the child, and being known in the community as the parent. The longer this has gone on, the stronger the estoppel argument. A man who learns of a paternity question when the child is two months old is in a very different position from one who waits until the child is twelve.

The Pennsylvania Supreme Court has identified several factors lower courts should weigh, drawn in part from the Uniform Parentage Act: the child’s age, how long the man acted as a parent, the nature of the relationship, the harm the child would suffer if it were severed, and how long the man waited after learning he might not be the biological father before filing.² That last factor carries more weight than people expect. Delay hurts every paternity challenge.

Who Can File

The presumed father. A man who signed an AOP, was married to the mother at the time of birth, or was declared the father by a court.
The mother. She can challenge an existing paternity determination, including one based on her own earlier acknowledgment.
A man claiming to be the biological father. An outside man who believes he is the child’s true father can seek to establish his paternity, which functionally challenges the existing legal father’s status. He still has to clear the estoppel and best-interests hurdles above.

A party requesting genetic testing must support the request with a sworn statement. The court or domestic relations section is then required to order testing of the child and the parties.³ The court will not order testing, though, if it first finds that estoppel applies or that testing would not serve the child’s best interests.

Filing the Petition

File in the Court of Common Pleas in the county where the child lives or where the existing support order was entered, typically through the Domestic Relations Section. You will need the full legal names and addresses of the mother, the presumed father, and the child, plus the child’s date and place of birth and the details of any existing support order.

The form depends on what you are attacking. To contest an AOP, file a petition to challenge the acknowledgment. To undo paternity established by a prior court order or the marital presumption, the filing is generally styled as a petition to disestablish paternity. Forms are available from the county courthouse clerk and, in some counties, the court’s website. The petition has to state the legal basis clearly: fraud, duress, material mistake of fact, or newly discovered evidence of non-paternity.

Filing fees vary by county but sit at standard civil levels. After filing, you are responsible for making sure the other party gets formal notice through proper service. The court will not move forward until the other side has been notified and given the chance to respond.

Genetic Testing in Court

If the court finds a valid basis for the challenge and no estoppel bar, it will order genetic testing. Pennsylvania requires the lab to be certified by the AABB (formerly the American Association of Blood Banks) or the American Association for Histocompatibility and Immunogenetics, with a proper chain of custody from collection through reporting. Certified records are admissible without additional authentication unless someone objects at least ten days before trial.³

The results carry defined legal weight. A test showing a 99% or greater probability of paternity creates a presumption of paternity, rebuttable only by clear and convincing evidence that the results are unreliable in that specific case.³ Under the procedural rules, an exclusion leads to dismissal of the paternity action, and a 99% or higher result leads to a stipulation of paternity.⁴

Cost works this way: when the court or domestic relations section orders testing, the section pays the initial cost. If paternity is ultimately established, the section can recover that cost from the alleged father.³ If you dispute the first result and want a second test, you pay for that one upfront. Court-admissible DNA tests typically run between $350 and $500, with prices varying by lab.

If a party refuses to submit to court-ordered testing, the court can resolve the paternity question against the person who refused. Skipping the test is treated as an admission.

What Changes If You Win

Disestablishment reshapes several things at once.

Child support going forward. The court terminates ongoing support. Pennsylvania has not adopted a blanket rule wiping out past-due arrears that accrued while the order was in effect. Whether existing arrears survive depends on the circumstances, and by statute support orders are not automatically suspended while a challenge is pending.¹
Custody and visitation. Custody or visitation rights tied to the legal father status end unless the court finds a separate basis for continued contact.
Birth certificate. Pennsylvania’s Department of Health allows removal or replacement of a parent on a birth record. You need a court order reflecting the disestablishment and a formal request to the Bureau of Vital Records.
Taxes. The disestablished father can no longer claim the child as a dependent, which ends the Child Tax Credit and related benefits.
Inheritance. The child’s right to inherit from the disestablished father, and his right to inherit from the child, are extinguished.

The consequences cut both ways. A successful challenge sheds the obligations and the legal relationship together. There is no version of the outcome that drops financial duties while keeping parental rights, and the result is very hard to reverse once it takes effect. Anyone weighing this proceeding should confirm that the legal outcome matches what they actually want before filing.

1
Pennsylvania General Assembly. Pennsylvania Code Title 23 Chapter 51 – Section 5103
2
Pennsylvania Courts. Sitler v. Jones, J-58-2024
3
Pennsylvania General Assembly. Pennsylvania Code Title 23 Chapter 43 – Section 4343
4
Pennsylvania Code and Bulletin. 231 Pennsylvania Code Rule 1910.15 – Paternity