in the imperial city i overheard a city watchman and one of the Atius members taking about how Doven Aren trains alteration when Atius pointed out that there was a Levetation act wich upset Doven when was the levatation act passed because i don't quite seem to recall it in the timeline book i read once in Skyrim

Its just a bit of convenience-lore.
A way to explain away why from morrowind to Oblivion we lost levitation.

I dont take it too seriously.
The levitation act would only apply to Imperial instituations such as the Mages guild and the College of Battlemages.
The Telvanni, the Psijics, the necromancers and any number of other organisations would have no reason to obey it.

The Septim Empire is now defunct and so is the Mages guild.
I cant imagine why there would be a levitation act in the Tamriel of today.
I believe that gameplay and lore differs quite a bit here, as I believe mages to be vastly more powerful than portrayed in games.
Leviation, teleportation, spellmaking, all these things are still very much present in the Tamriel magic lore in my opinion.

ok then

Mind, the Levitation Act could be more than just statute.

You mean a change in magic itself?
I dont think that likely.
At the height of the Septim Empire the Imperials may have had the arrogance to decide such a thing for the whole of Nirn, but I dont think that at the end of the third era they had that kind of hubris.
Would other powers go to war over somehing like this, the PSJJJ, the Telvanni?

It could be however.
Maybe old Uriel thought it his last great act.

The idea of warring over wether or not people should be alllowed to levitate amuses me greatly.

Perhaps when Nerever slew Almalexia, her prohibition over levitation grew out of control. Like an infectious creep, the pestilent antispell slithered its way out into greater Tamriel, sowing its seeds in every corner of the Nirnic Wheel.

Now unreliable, sometimes working, sometimes doing nothing, sometimes overshooting a mananaut straight into the Sun, the lawhappy Imperials poot their fut down, declaring Levitation illegal, waiting until Almalexia's magic erased the last of the float-magic's tendrils.

Then, circa 5 to 10 4E, explorers investigating the reaches of the North made a horrid discovery. Sky whales. Sky whales plastered about the frozen tundra.