The process of policy layering - in which new goals and means are added to, or layered on, existing ones – has attracted recent scholarly attention as part of the broader project of cataloguing the many different policy dynamics beyond the stability-change dualism. Despite its popularity as a term and its intuitive appeal, layering has yet to be fully distinguished analytically from other well-known concepts such as ‘muddling through’ or the change processes of ‘conversion’ and ‘drift’. This paper investigates transport biofuels as case of policy layering, where ambitions in terms of sustainability and energy have layered a number of competing and incommensurate values onto extant agricultural policy legacies. A strategy of temporal separation has been designed for this problem of layering: some values (e.g. sustainability) were given superordinate goal status but pushed into the longer term; potentially conflicting values (e.g. rural development) were enshrined in shorter term objectives. This paper will use the biofuels case to explore the policy-maker’s dilemma of maintaining long-term policy layers as credible commitments, despite the flexibility and adaptability in policy-making required to achieve them under high political, technological and market uncertainty. In doing so, the paper contributes to the refinement of the concept of policy layering, notably by offering conditions under which it might render policy problems ever more wicked, and those contexts in which layering provides for policy resilience in the face of the unknown unknowns of policy making.
