that was a good read, but, I don't think the term "generally illegal" will apply to it. The only thing that supreme court case provided that that a road block can lead to a seizure, which triggers the fourth amendment protections. That doesn't outlaw the roadblock, or does it mean it will be a violation of the fourth amendment as generally speaking seizure under the fourth amendment has leniency that allows for probable cause and a reasonable approach. It means that road blocks need to be looked at when done and decided if it was a reasonable method of stopping them.

In the specific case listed, it was passed down to the lower court again to decide whether the roadblock was a reasonable use of force or not, so it was never an argument about whether the roadblock was allowed to be done, but whether or not how they implemented the roadblock was reasonable due to the fact it was constructed around a corner and contained lights that were positioned in a way that would blind drivers coming in.