Many postdocs working in the US as research scholars are here on the J-1 visa. The J-1 visa is a temporary visa classification, and it actually does not allow for dual intent. Dual intent refers to the idea that a foreign national can hold a particular temporary visa classification and have the permanent residence (green card application) underway at the same time. The dual intent doctrine applies to the H-1B, L-1, O, and P categories, and is also recognized for persons with E status. However, the doctrine of dual intent does not apply for persons holding J-1 status. It is technically possible to start the green card process while in J-1 status, but once the immigrant visa petition is filed (the I-140 petition if filing through the employment based process, such as the EB-1 Alien of Extraordinary Ability or EB-2 National Interest Waiver petition), you cannot extend the J-1 status, and you cannot travel outside the US and re-enter in J-1 status.
On the other hand, it is possible extend H-1B status or travel on the H-1B visa and file an EB-1 or NIW petition (or any other permanent residence filing for that matter). Because of that, it is sometimes said that it’s easier to file the EB-1 or NIW when you hold H-1B status, rather than J-1 status. This is partially true: it is easier in the sense that you can still extend your status and travel internationally while in H-1B status. On the other hand, the actual process of gathering the required evidence, assembling the petition, etc is not any harder or easier regardless of your immigration status.
The bottom line is that while there are benefits to filing for permanent residence while in H-1B status, it can be done while a person is in J-1 as well. Sometimes the benefits of having a green card in hand sooner outweighs the challenges associated with the process. If you are interested in starting the permanent residence process, please email your updated resume to firstname.lastname@example.org. We offer evaluations and consultations for professors and researchers interested in the EB-1 and NIW options. We look forward to hearing from you!