The objective of an expert report is to provide justification for the expert’s conclusions and opinions. Anyone who has worked with an expert witness knows the expert report is constantly evolving. Whether it is adding “legalese” or simplifying difficult concepts for the jury or judge, an expert report is a joint effort between the attorney and the expert witness. However, what level of co authorship is allowed? Moreover, at what point do the expert witness and his report become an alter ego of the attorney? When does the report’s author become the attorney’s report with the endorsement of the expert? In late 2014, two cases addressed these issues and now serve as a reminder to counsel of their proper role in drafting an expert report.