Abstract

The iterative advancement of Transfer-DNA analytical techniques has provided a novel means of proof for indecent assault cases, which typically lack objective physical evidence. However, this trace, probabilistic evidence—constrained by extremely low template quantities, susceptibility to degradation, and multi-stage transfer—has exposed prominent challenges in both Chinese and U.S. judicial practice: the evidentiary status of negative results remains ambiguous; indirect DNA transfer undermines causal proof; and mixed profiles and third-party contamination yield divergent interpretations. Owing to differences in litigation structure, scientific evidence review, and forensic standardization, the two countries diverge sharply in admissibility review, activity-level proposition use, expert witness systems, and quality control. The United States has built a filtering mechanism grounded in the Daubert standard, SWGDAM guidelines, and case law, yet faces inconsistent standards due to juror bias and fragmented federal-state legislation. China has seen growing application but lacks specialized rules, producing a pervasive adjudicative error in which sub-source-level conclusions are directly extrapolated to criminal activity findings. Employing a comparative-law methodology, this article analyzes the threefold causes—technical, normative, and judicial-cognitive—and constructs a full-chain solution tailored to indecent assault scenarios. Its core argument is that these dilemmas are essentially a normative question of how probabilistic forensic evidence can be embedded into the traditional criminal corroboration-based proof system; only coordinated upgrading of technical standards, evidentiary rules, and judicial cognition can realize Transfer-DNA's value while preventing wrongful convictions.

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