The success of open source software (OSS) projects relies on voluntary contributions from various community roles. Among these roles, being a committer signifies gaining trust and higher privileges in OSS projects. Substantial studies have focused on the requirements of becoming a committer in OSS projects, but most of them are based on interviews or several hypotheses, lacking a comprehensive understanding of committers’ qualifications. To address this knowledge gap, we explore both the policies and practical implementations of committer qualifications in modern top OSS communities. Through a thematic analysis of these policies, we construct a taxonomy of committer qualifications, consisting of 26 codes categorized into nine themes, including “Personnel-related to Project”, “Communication”, and “Long-term Participation”. We also highlight the variations in committer qualifications emphasized in different OSS community governance models. For example, projects following the “core maintainer model” place great importance on project comprehension, while projects following the “company-backed model” place significant emphasis on user issue resolution. Based on the above findings, we propose eight sets of metrics and perform survival analysis on two representative OSS projects to understand how these qualifications are implemented in practice. We find that the probability of gaining commit rights decreases as participation time passes. The selection criteria in practice are generally consistent with the community policies. Developers who submit high-quality code, actively engage in code review, and make extensive contributions to related projects are more likely to be granted commit rights. However, there are some qualifications that do not align precisely, and some are not adequately evaluated. This study contributes to the understanding of trust establishment in modern top OSS communities, assists communities in better allocating commit rights, and supports developers in achieving self-actualization through OSS participation.