This paper examines patent oppositions as ﬁrm-level responses to newly-granted patents. We present a citation-based construct for measuring the technological lineage to which a newly granted patent lays claims. This network-analytic construct, which we label technology trees, allows us to develop a reﬁned explanation of patent oppositions by taking into account the ownership structures of the technology to which a particular patent relates. An application to the cosmetics industry reveals that the technology tree measure, which is calculated on the level of individual patents, usefully complements established network measures at the industry level, such as triplet counts for measuring patent thickets. This suggests a need for further and more ﬁne grained analyses of technology trees as context in which patent oppositions play out.