The U.S. FDA’s September 2022 guidance for clinical decision support (CDS) software was controversial the moment the agency posted the document, prompting the filing of a citizen’s petition five months later. The CDS Coalition has penned a June 8 letter to FDA commissioner Robert Califf in an effort to draw a reaction from the agency, but the letter was accompanied by a summary of an analysis of CDS software with a machine learning (ML) component that suggests that such products that are in development may have to be reconsidered.