The Casimir force between parallel lines in a theory describing condensed vortices in a plane is determined. We make use of the relation between a Chern-Simons-Higgs model and its dualized version, which is expressed in terms of a dual gauge field an
d a vortex field. The dual model can have a phase of condensed vortices and, in this phase, there is a mapping to a model of two non-interacting massive scalar fields from which the Casimir force can readily be obtained. The choice of boundary conditions required for the mapped scalar fields and their association with those for the vectorial field and the issues involved are discussed. We also briefly discuss the implications of our results for experiments related to the Casimir effect when vortices can be present.
