Abstract: Machine learning systems and methods for validating workflows are provided. The system receives one or more digital images of a work action being performed, and processes the image using a hierarchical modeling process that includes a filter model and a cascaded expert model. The filter model processes the image to ascertain whether the image is suitable for use in validating completion of the work action. If the system determines that the image is suitable, the image is then processed by the expert model to classify whether the image depicts a scene occurring before, during, or after performance of the work action. The hierarchical modeling process can be utilized to validate different workflows based upon a specified workflow type. A plurality of hierarchical modeling processes can be applied in parallel to an input image in the event that a type of workflow to be validated is not specified in advance.