More horrible watering down and demeaning of what an arrest is.
When you are seized in any form you are arrested. The courts as PALO points out is not the friend of your liberty as you can see by his cites.
In my states and for much of history any detention slash arrest was done with a warrant or if the felony was witnessed, now in my state you can be arrested only if the cop sees you commit the misdemeanor, then many courts catering to the rise of the police state have decided that PC wasn't good enough that this constitutional limit was to restrictive, so they invented RAS.
Any time any Popo or prosecutor or judge or statist use these rationalizations I will be quick to point out how unliberty it is.