question: why is is the copy effects layer ahead of the control layer? the only card I know of that cares about that order is Volrath's Shapeshifter, and it would prefer the other way around. what interactions would splode if they switched them?

Because if it was the other way around, using Copy Enchantment on Persuasion wouldn't do anything.

Copy Enchantment copying Mind Control wouldn't work if the order was reversed

that makes sense

thanks rules nerds

is that the only one? because layers have been around since long before Ravnica. was it the other way around before then?

The only change I recall being made to the layer system was adding sublayers to handle various power and toughness modifications/effects. There was a point in time when setting a creature's power and/or toughness (like with Ovinize or Vhati il-Dal) would cancel out effects from stuff like Giant Growth or Darkblast.

I think it was the 6ED rules changes that nerfed Island of Wak-Wak and company. Until then,. P/T changes were strictly timestamp order

No, copy effects have had first shot since the creation of the layer system.

I don't have any actual knowledge of what went through R&D's heads at the time, but if I had to guess, I'd say that even if the specific interaction wasn't possible yet when the layer system was created (I'm not sure whether or not it was), R&D would have been faced with a choice. By its very nature, the layer system's existence makes it impossible for R&D to reasonably print certain kinds of cards--how it's set up defines what kind of cards they can make. Color after type? Then they can't print "Green creatures are Elves." Power and toughness last? Then they can't print "Creatures with power 1 or less have flying". And so on.

If R&D set up the layer system to allow Volrath's Shapeshifter to work as expected, they either wouldn't be able to print any card that allowed players to copy anything with a Control Magic-type effect, or they'd have to get rid of Control Magic-type effects entirely. But if they set it up in a way that threw Shapeshifter under the bus, they would only be unable to create cards that could change what they were a copy of based on control of objects, which is of course a much smaller area of design space. So Shapeshifter got bussed.

Before Ravnica you could play Copy Artifact copying Control Magic with a little help from Mycosynth Lattice

Layers are called layers since Mirrodin. They have changed a few times. Originally layers 5 and 6 (color changing and ability changing) were just one layer, but then Snakeform and the deity auras caused the layer to explode into two. At this time they also reorganized the power and toughness sublayers.

Also, originally the power and toughness layer didn't have sublayers, but effects from CDAs (formerly called CSEs/CSAs, characteristics-setting effects/abilities) were applied first, then effects from counters, then everything else. Oh, and effects that changed types applied fully in layer 4, even the parts of the effect that set power and toughness.