Political Science Expert Was Allowed to Opine on Paraguay’s Legal System
Posted on December 9, 2025 by Expert Witness Profiler
On September 12, 2025, Maik Evert Ens Loblein (“Petitioner”) filed the Petition for the Return of Children to Paraguay pursuant to the Hague Convention. The Petition asserted that Roxana Andrea Alcaraz de Ens (“Respondent”) unlawfully retained in the United States two children who habitually reside in Paraguay. On September 15, 2025, Petitioner filed an Amended Verified Petition for the Return of Children to Paraguay.
On September 18, 2025, pursuant to the Court’s order, a temporary restraining order was entered preventing the removal of the two minor children, S.I.E.A. and M.A.E.A., from their location within the jurisdiction of the Court. By stipulation of the parties in this matter, the Temporary Restraining Order was extended until further order of the Court after the Amended Verified Petition for the Return of Children to Paraguay is resolved on its merits.
Respondent designated Dr. Aníbal Pérez-Liñánto offer expert testimony regarding Paraguay’s legal system, including its institutional capacity to protect victims of domestic violence, enforce protective orders, and maintain an effective system of criminal accountability.
Petitioner filed a motion to exclude the testimony of Respondent’s expert Aníbal Pérez-Liñán.
Political Science Expert Witness
Aníbal Pérez-Liñán is a Professor of Political Science and Global Affairs at the University of Notre Dame as well as Director of the Kellog Institute for International Studies.
He holds a doctoral degree in political science, with a specialization in Latin American Political and legal institutions.
He has authored two books related to Latin American political systems peer-reviewed publications in the American, Journal of Political Science, Comparative Politics, and others, and served in editorial leadership on major academic journals. Additionally, his research includes Paraguay’s compliance with the Inter-American Commission on Human Rights, and he has served as a consultant for the Paraguayan Supreme Court to prepare a report on Paraguay’s compliance with human rights laws, which includes domestic violence.
Discussion by the Court
Whether the Specialized Knowledge of Aníbal Pérez-Liñán Will Assist the Trier of Fact
Petitioner argued that Aníbal Pérez-Liñán’s experience is insufficient to support his opinions regarding the ability of Paraguay’s legal system to address cases of domestic violence. The Court disagreed.
In other words, Aníbal Pérez-Liñán’s experience and knowledge are sufficient to qualify him as an expert on Paraguay’s legal system, including its institutional capacity to protect victims of domestic violence, enforce protective orders, and maintain an effective system of criminal accountability.
While Aníbal Pérez-Liñán has conceded he would not consider himself an “expert on domestic violence in the Paraguay legal system” he would consider himself “an expert of the Paraguayan legal system more broadly.”
The lack of specialized knowledge of domestic violence in the Paraguay legal system would go to the weight of the testimony, to be judged by the trier of fact, and not serve to disqualify Aníbal Pérez-Liñán as an expert. Therefore, Aníbal Pérez-Liñán possesses sufficient knowledge and experience such that his opinion would help the trier of fact evaluate the extent to which the minor children would be sufficiently protected by the Paraguayan legal system, which clearly informs the “grave risk” analysis under the Hague Convention.
Whether Aníbal Pérez-Liñán’s Testimony is the Product of Reliable Principles and Methods
Petitioner argued that Aníbal Pérez-Liñán’s opinion is not the product of reliable principles or methods.
In support of this assertion, Petitioner claimed that Dr. Aníbal Pérez-Liñán “relies on a single, moldy study that analyzed a small handful of cases, along with two newspaper articles.”
However, Aníbal Pérez-Liñán testified that he reviewed Paraguayan statutes and regulations governing domestic violence, analyzed institutional reforms dating back over two decades, examined NGO, government, and international data repositories, and consulted institutional actors to confirm real-world practices.
As an experiential expert witness, Aníbal Pérez-Liñán’s methodology need not necessarily be supported with peer-reviewed journals and testable methodologies. These are all standard methodological tools of a type that would be reasonably relied upon by experts in Aníbal Pérez-Liñán’s field.
Thus, on the record here, the Court is satisfied that methodologies employed by Dr. Aníbal Pérez-Liñán are the product of reliable principles and methods under the requirements of Daubert.
Whether Aníbal Pérez-Liñán Has Reliably Applied the Principles and Methods to the Facts of this Case
Petitioner raised no objection to whether Aníbal Pérez-Liñán has reliably applied the principles and methods to the facts of this case. However, this Court is satisfied that such generally accepted methodologies have been soundly applied to the facts here. In any event, the proper way to test the correctness and thoroughness of an expert’s opinions is through cross-examination and rebuttal evidence. If Aníbal Pérez-Liñán’s views are shown to be arbitrary or groundless, then the Court can give the testimony no weight.
Held
The Court denied the Petitioner’s motion to exclude Respondent’s expert Aníbal Pérez-Liñán.
Key Takeaway
For testimony that is primarily experiential in nature as opposed to scientific, there are meaningful differences in how reliability must be examined. Inquiries into testability, peer review, and error rates may not necessarily apply. Instead, a Court may focus on whether the experiential expert “employs in the courtroom the same level of intellectual rigor that characterizes the practice of an expert in the relevant field” and whether the expert’s reasoning or methodology has general acceptance in the relevant professional community.
Case Details:
| Case Caption: | Ens Loblein V. Alcaraz De Ens |
| Docket Number: | 3:25cv737 |
| Court Name: | United States District Court, Virginia Eastern |
| Order Date: | December 03, 2025 |
