Legality of the cartridge has no bearing on whether or not it is a smart and humane way to kill a whitetail. If you surveyed 100 people I bet you might be able to find one who could give an example of a law in this country that was not a good move on the part of the government.
The largest roe I have killed may have run 45#if he just finished eating and it was pouring rain on him and he had his full winter coat. And this was in far southern England where they are larger than their northern kin. Please tell me how well it worked for you on some of the roe you have shot.
And please re-read my post where I said it could be done, but it was not a smart move.
Sorry for the rant, but I took your post as rather snotty, which is far different then I normally see your posts. If it was not menat as such, then pretend I did not write the above verbage. If you were trying to be snotty, then please read the above verbage again.