To use my own personal experience on this, at Caltech from 2008-2014, I was an assistant staff scientist for five years until I was cross-promoted to an assistant research scientist in my final year there. Like faculty, we had a "class" system as well; we were divided into "staff" and "research" scientist tracks. The expectations were also different for each track - 80/20 vs 50/50 programmatic / research focus. Of course, the research scientists liked to joke it was 80/80, because programmatic work didn't decrease, but that's another story. Like term faculty, the staff scientists were paid less than the research
scientists. We also had promotions within rank - assistant, associate
and full - just like faculty. Just like for term vs. tenure faculty, there were higher expectations of leadership, publications and grant funding among the research scientists relative to staff. There was also more job security on the research track. The similarity to the term vs. tenure lines was intentional. The research scientists also usually occupied the leadership roles. Unlike the term/tenure faculty example, there were many more staff than research scientists.
For me what made this "class" system tenable at Caltech was a key difference - there was a clearly defined and communicated pathway by which one could transition from the staff to the research track. The criteria: performing at the level of the research track scientists. Incidentally, that was also the criteria for promotion within each track, demonstrating performance at the next level already (with a written description of what that meant). Yes, it meant working harder, carving out extra time for research when we already had high-levels of programmatic burdens.
I am unaware of any University that has a clearly communicated pathway from term to tenure faculty, and perhaps that is a result of the administrative drive nationwide to minimize the number of tenure faculty. However, I think we could pursue defining such a pathway in future years - by we I mean my institution. These issues already often come up for term faculty and research staff; the lack of a clear path from non-tenure to tenure lines leads to inconsistencies, unfairness, and frankly term faculty leaving their institutions. This problem has been brewing nationwide for decades as the fraction of term faculty has steadily increased; long-standing trends in administrative policies to save money are coming home to roost.
At Mason, we don't have a clear, written policy on a "sideways" promotion across tracks for faculty, as Caltech did for its science staff. There doesn't exist a national solution to this problem. However, if we could develop a "sideways" promotion criteria, it could be a game-changer in terms of showing how to alleviate the class structure that exists between term and tenure track faculty. As of now, there's an insurmountable barrier, short of winning an open job search. Having a coherent and solid annual performance review process in place is a prerequisite. Caltech did have such an annual review process - We submitted written reports and our bosses wrote written, one page evaluations. Then we had a sit down, in person meeting on every year to review. I used to dread the meetings, but they were always relatively informal and collegial; I grew from them as a scientist and I got honest feedback on my job performance and where I could improve. Our boss and then an ombudsman for the scientists would attend. The ombudsman - a head of science staff - helped protect against favoritism of individual bosses, and got a 30,000 foot view of the whole organization to help guide the bosses too.
There is also a way to sell this to a Provost or University administration: at Caltech, since this process existed, it enabled Caltech to stack the decks heavily with more lower-paid staff scientists, and relatively fewer better-paid research scientists - even more extreme an imbalance compared to the typical ratio of term to tenure faculty. By allowing the pathway for term faculty to become tenure line, I think most Provosts would fear that this would cost them more money. But instead the opposite happened for Caltech - the staff scientists knew what they had to do to get to research faculty as it was clearly communicated; they had to be the best, and it was just very hard. Very few of us successfully made the transition, but many of us tried. This meant more grants, and more publications, this meant more commitment and effort from everyone. As a result, Caltech was able to grow its staff of scientists to be much larger than its research faculty; the role of research scientist was reserved for those that had consistently over-performed for years. And thus I think this would be consistent with long-term trends for Universities to increasingly rely on term faculty. As much as we malign this situation, and would rather increase the number of tenure-line faculty, this nationwide trend does not seem to be reversing any time soon.
The system at Caltech wasn't perfect; far from it; I did decide to leave one of the top institutions in the world for my field of study to become an assistant professor at Missouri State. I had burned out at Caltech. However, if we don't do something like this, as the number of term faculty only continues to grow (w/r/t to the number of tenure faculty) with no outlet, I think the resentment and class structure we have will only get worse. There needs to be a way to tunnel through the barrier. Anyway, that's my two cents tonight. Let me know what you think.