Enchantments and protection

[An Angry Fatman]

i have an {arrest} on target creature. A few turns later, he gives it protection from white. Is it grandfathered in to still be attached to the creature??

[Nfidel2k]

702.16c - auras can't be attached to a permanent with protection from a quality of the aura.  It's a state-based action that sends the aura to the graveyard.

[redwolv]

It is why  {Spectra Ward} has specific text, otherwise it would remove itself.

[An Angry Fatman]

So wait, I am still not getting the message here. Does it fall off or does it grandfathered in? I am just having trouble understanding the concept.

[Mr_Fahrenheit]

It falls off. Think of it as constantly targeting and by giving protection you cause it to become an invalid target and it falls off the next time it tries to target  (the next time player would receive priority).

[An Angry Fatman]

Ok, I got it now. Thanks guys!

[Spikepit]

Off topic, but I'm wondering, what does 'grandfathered in' mean? Is it a new American slang for something or was it autocorrected twice by accident?

[Nfidel2k]

"Grandfathered in" means something that applies because it existed before a change, usually a change in rule or law that prevents or prohibits that thing.  It has to do with the concept of ex post facto - that someone can't be held responsible for an illegal act that was committed before the act was declared illegal.

I keep trying to think of a mtg example, but the closest I can get is an epic spell.  Magic doesn't really use the "grandfathered" concept.