The L1 penalty with coordinate descent solver for GLM was proposed in https://github.com/scikit-learn/scikit-learn/pull/9405 and was not included in the minimal implementation merged in https://github.com/scikit-learn/scikit-learn/pull/14300. It would be be good to add it, however care must to taken to avoid redundancy with the existing coordinate descent solver in ElasticNet. Preliminary benchmarks were done in https://github.com/scikit-learn/scikit-learn/pull/9405#issuecomment-499578511 Also see: https://github.com/scikit-learn/scikit-learn/issues/16634 https://github.com/scikit-learn/scikit-learn/issues/16635