A Sewel motion is a motion passed by the Scottish Parliament, in which it requests Westminster to pass legislation on a topic extending to Scotland. It is generally used when Westminister is considering legislation extending only (or having provisions extending only) to England and Wales, and the Scottish Parliament, being in agreement with those provisions, wishes for Westminister to extend them to Scotland also, rather than requiring separate, identical legislation to be passed by the Scottish parliament.
This generally may be used, for non-controversial matters, for the purposes of legislative economy; it also may be used for more controversial matters, where the Executive does not wish to have the Scottish Parliament to consider the issue in detail, to avoid the political consequences, and to keep the legislative bickering to Westminister only.