The concept of Sustainable Forest Management (SFM) has a pivotal role for both the Cameroonian legal framework and market-based instruments such as forest certification. We assess the different impacts on timber harvesting of the forest legal framework as compared to the adoption of forest certification, on the ten Forest Management Unit (FMUs) that had received a Forest Stewardship Council (FSC) certification by mid-2009, and discuss some differences between legal and certified timber. Results show that the average reduction in the annual allowable cut (AAC) of concerned FMUs is about 11% when legal harvesting rules are adopted, about 18% when the FSC rules as requested by the certifying bodies (CBs) are applied, and about 34% when the 'FSC logic of sustainable harvesting', as agreed upon on paper by logging companies and CBs, is used. Our findings confirm that forest certification has the potential to improve weak normative frameworks that allow the unsustainable use of forests. However, they also suggest that certifying bodies tend to reduce the stringency of the FSC rules in certified FMUs if not backed by a uniform FSC standard and by a stronger legal framework. We elaborate on the reasons why that may occur and provide suggestions for improvements.