That would be but it was the 1970s?
Similar things go on right now, they just aren't as easy to explain because they are not well known. And you aren't answering the question. For institutional racism to exist does it have to be in a written rule or policy? EDIT: Wait, I misread your answer. You did acknowledge that it "would be" while throwing on a deflector to imply that even though it would be that doesn't matter since it (maybe) isn't current.
But, let's try a current example.
A guy I work with; licensed contractor, makes a point of always having me on the job site when there is an inspection due, and always takes me with him to building and safety. Now, I get paid by the day and frequently a day with an inspection is pretty much wasted on doing petty little stuff and waiting, and obviously no work gets done at the building and safety office, so why do I get paid for "working" these days? Because I
always get better results. The various city and county building and safety departments don't have any written policies that say "treat the white guy better," and I don't really think that every single inspector in every place that we work is slanted by their individual racism. But there is a definite collective result, and it isn't small.
My partner, in several decades as a contractor, has hardly ever gotten through an inspection without having to plead over some petty issue and kowtow to the inspector to get passed. I can't remember the last time I got a work stop over anything that wasn't a glaring piece of outright cheating the plans (yes, we do that occasionally, and sometimes we do get caught). If he even tilts the least bit towards complaining to somebody the response is basically "I dare you and you will never get a job approved in this town again." If I get the least bit irritated and say "who is your supervisor?" I almost always get an immediate sign off and retreat.
The first time I went to B&S with him we had this list of agencies that he had been given who "had to" sign off on this project we were doing for our church; there were like ten. He had handed it off to me and I had gotten one signed and found out that three were total wild goose chases. We walked in as the office opened and I was snarling "I want to see <guy who had given him the list>" with enough venom that people were seriously wondering if there would be blood. Girl at the counter says dude is apparently late for work
and offers us coffee. Guy walks in and I rush him before he even makes it behind the counter, start with a "This signature you demanded, the agency says they have nothing to do with it. This one you listed a school district that we aren't even in, and they told me that it doesn't matter because we don't need a school district sign off anyway. This one they said that they give approval on line and it is handled through your office so they didn't know why I had driven all the way down there. I don't know about the rest...y'know what, screw it, where's your boss? I can't even look at you much less talk to you about this." At this point the rats are scurrying all directions, the other customers are all gaping (and silently applauding no doubt) and the boss is promptly hauled out to the counter where he ranted at dude for all the BS stuff he had written on our plans as requirements, voided them all except the one I had already gotten signed, and thanked us for our patience about the misunderstanding. My partner noted as we left "If I acted like that they'd have called the cops in the first thirty seconds, and I'd be lucky to get away without being shot." To this day when we do work in that county that guy basically signs off any plan we come in with without even looking up and meeting me eye to eye.
Was everyone in that office a racist? To some degree, maybe. But what really makes the difference is that everyone, racist or not, knows what they can and can't get away with. They call the cops on me I'm going to tell the cops my tale of woe and the cops are going to say "well, you people can't just do infuriating stupid stuff here and expect people not to get mad." They call the cops on a dangerous brown man and he wouldn't get two words out before he was looking down a gun barrel. So whether they are
individually racist or not doesn't matter. And that is the definition of institutional racism, with or without written policy.
