There's talk about one of the bigger schools "nearby" (and "nearby" is relative, and means within a gas-tank's drive) that they've got a rule about adjuncts not teaching more than three consecutive years. So people who've gotten degrees there often take adjuncting work there, but after three consecutive years, they can't teach there for at least one full semester.
One one hand, local lore has it, the policy prompts adjuncts to move on and get on with their lives, either to other adjuncting elsewhere or to leaving academia (or, if they hit the jackpot, to a TT job somewhere). And so, the policy-makers assure us, the policy is for the benefit of the adjuncts.
It also means that newer graduates can get a couple years of teaching under their belts to help them get experience and have time to look for the elusive TT job. It also reduces the likelihood that adjuncts will be around long enough to get together and try to improve things.
I can see wanting to give newer grads a chance to get some experience; that seems reasonable. Though weirdly, it also means that those who've gotten the experience are less employable, which is weird.
But claiming that it benefits adjuncts to be forced out seems hugely paternalistic, doesn't it? Who's to say that the adjunct isn't geographically bound for some reason and wants to continue adjuncting (though we all know it's not an ideal for most of us). A lot of decisions other adults make seem less than ideal to me, but I respect their decisions. (I'm sure my own decisions seem equally less than ideal to many people.)
As with so many decisions about adjunct hiring, damned if you do, and damned if you don't.
In the interests of full disclosure: I adjuncted for a year after finishing my phud at the school where I'd studied, and then I got the brass ring, of sorts. And now my teaching load is lower than it might be because my school employs adjuncts at a lower cost than TT faculty; we've dealt with budget shortfalls by hiring adjuncts more and more.