Understanding how to distinguish the prior art is a fundamental aspect of practicing patent law. One common area that trips up even experienced practitioners is the distinction between the prior art missing a feature of the invention, and the prior art having an additional feature compared to the invention. When put this way, the distinction is clear and as everyone knows - the former is an argument in favor of patentability whereas the latter is not. Yet, the distinctions between these two can blur substantially and cause hiccups in drafting and prosecution.

Today we review a medical algorithm invention (Appeal 2021-004018, Application 14/496,025) related to work being conducted by the University of South Carolina. The specific area of the invention is ultrasonography training. Claim 1 on appeal is below:

1. A method for conducting ultrasonography training using ultrasound loop control, the method comprising:
providing for display, with a computing device, a moving ultrasound image of an internal body part within a user interface as part of an ultrasound training exercise, the moving ultrasound image associated with an image frame loop including a plurality of individual image frames, the user interface including a first interface element associated with stopping the moving ultrasound image, a second interface element associated with cycling the image frame loop forward or backwards, and a third interface element associated with selecting an image frame of the plurality of individual image frames;
receiving, with the computing device, an initial user input via user interaction with the first interface element that is associated with stopping the moving ultrasound image at a current image frame of the image frame loop;
receiving, with the computing device, a second user input via user interaction with the second interface element associated with cycling forward or backwards through the image frame loop in order to provide additional image frames of the image frame loop for display to the user;
receiving, with the computing device, a third user input via user interaction with the third interface element that is associated with a submission of one of the plurality of individual image frames as a user-selected image frame for performing a given examination task;
in response to receipt of the third user input, accessing, with the computing device, assessment data associated with a pre-defined correct image frame for performing the given task during the ultrasonography training; and determining, with the computing device, whether the user-selected image frame corresponds to the pre-defined correct image frame based on the assessment data.

The examiner applied a combination of prior art. One of the applicant’s primary arguments was that the prior art taught identifying, from a plurality of image frames, an image frame that depicts a particular pathology and that selection of an image frame that depicts a particular pathology is not what is required in the claim. However whether the prior art performed some additional step (depicting a particular pathology) does not take away from the fact that the prior art taught selecting an image from a plurality of frames.

As succinctly explained by the Examiner, “[t]he pathology depicted on the image does not negate the teaching of Pedersen as applied to the claimed limitation,” because the user in Pedersen “is still selecting an image frame (from the plurality of image frames) regardless of whether the user selected the image frame due to the pathology it is depicting.”

A drafting tip: When there is potential for broad claim interpretations to lead to the idea that the invention enables simplified operation or skipping certain steps, it can be beneficial to lay out such details explicitly as at least an example embodiment. Since it can be difficult to avoid reading on the prior art when the only difference is that the prior art has extra features, potential amendments that exclude the extra feature are an option to consider.