jats:p This article investigates the social life of excision at the Southern Spanish border. Scholars have documented how excision expands the border project, and how it uses the law to make it more defensible as a practice. Less attention has been paid to how excision is challenged by activist networks, and how the law is used as an instrument to un-make borders. I expand literature on the complex relation between the law and geography in bordermaking by arguing that excision is rather dynamic in nature. A comparative ethnography of Melilla and the Canary Islands reveals that de facto borders created through excision are vulnerable to legal activism. The strategic use of the law can set back the expansion of the border project, tenuously restoring some rights for asylum-seeking and undocumented foreigners. Such setbacks are tenuous because excision is, nevertheless, deeply integrated into a dense web of containment tactics. ‘The undesirables’ might thus recuperate some of their rights at one point but then still face exclusion at another point of the expanded frontier. </jats:p>