Lawful Interception (LI) refers to a lawfully authorized process of looking into private communication under a court-issued warrant. Quite a number of countries have been drafting and enacting laws authorizing the LI procedures on packet-switched IP networks including traditional circuit-switched ones. As the IP mobility becomes more ubiquitous, propelled by wireless networks, it becomes an issue in the LI domain to keep track of a migrating target. However, with the world's focus on the current LI architectures, little consideration has been given to a seamless LI triggering, which accommodates IP mobility and vertical handover. Proposed herein are a seamless LI architecture and relevant triggering algorithms for the heterogeneous wireless networks. The simulation results demonstrate that the proposed architecture secures a seamless LI by capturing all the suspected target traffics without any time delay, which usually occurs during an LI triggering between different service providers. Furthermore, when compared with the existing LI architectures, the architecture significantly helps reduce transmission and the time consumed for analysis of the content of communication (CC) and intercept related information (IRI).