If you have been treated for a pre-existing long term health condition, and it's been covered by your medical insurance in the past, and then you switch jobs and change insurance companies, can they legally refuse to pay to treat that condition? Anyone here know?

When one fills out insurance forms for a new company, there's all this text in there about how they might not cover pre-existing conditions. That doesn't sound like it should be allowed, that's cheating.

If this is true, how do they get away with it? I mean, other than the fact that the insurance companies are all just a tiny step above Mafia protection rackets, which we already know.