In the first case, it's amazing how much the anti-mage side seems to trust abominations. First Marethari, now Uldred...
On the second note, yes, it is quite easy... provided the other conditions are met. I invite you to show me a single instance of possession occuring when one of those conditions wasn't in place.
It's an inherently unjust law, should not be defended, and cannot be practiced without corruption.
Seriously, I am not agreeing with Uldred about what he said, I was referencing both Wynne and Uldred's comments in the video Bioware officially released to introduce people to Abominations prior to DAO coming out that very clearly shows mages have to work very hard to avoid becoming Abominations. No I don't think Abominations are the end for all mages. Also, I am not anti mage, have you missed me arguing with both sides for the last 5+ pages?
Pro Mages(largely) see possession and Abomination as too unlikely to be worried about and having very few specific times and places where it can occur. They also entirely disregard the ability of mages to abuse just having magic to dominate others. They also view templars as only what has been shown largely in DA2 which were marginalized charactures of Templars admittedly by bioware so that both sides looked bad. Can you imagine how bad the mages would have looked if the templars in Kirkwall would have all been portrayed as Alistaire and Gregoire and the mages in Kirkwall were all still doing what they did? They made both sides worse. Also, they are only too quick to defend any horrible act a mage committs by saying it was justified because of Chantry/Templars.
Anti Mages(largely) see possession and Abominations as being way too easy, like a mage is going to sneeze and become and abomination. They tend to disregard the many good mages we have met that have demonstrated themselves to be quite able to resist tempations. They view the idiocy of all the blood mages in Kirkwall as proof of what all mages are like, even though no one in Asunder resorted to becoming an abomination or blood magic to resist the templars--again heavy handed game trope to make sure we all arrived at the place bioware wanted us for DAI. And much like their opposites are only too quick to defend most any act by a templar as without fault.
Seriously people: Fiona, Ariane, Rhys, Lambert, Evangeline, Wynne, Meredith, Orsino, etc etc etc have all been played very badly by someone we haven't met anyway. Seriously do ya'll think after 1000+ years a mage templar war just decided to happen? No someone has pulled the strings to bring this about for an exact purpose.
Oh yeah and inherently unjust law or not, Aenerin knew what the law was and can be thankful they didn't kill him. That excuse is like saying it is unjust when a prisoner escapes from prison and they have to use deadly force to capture him. A mage who leaves the tower without permission is just that a criminal, and they know it when they do it.