In England, at amatuer level a heavy tackle that gets the ball first, as long as studs aren't showing and he didn't jump into the tackle, is aknowledged as a good tackle because the ball is played. That's why players like Scott Parker, and more recently Owen Hargreaves are praised as being good midfielders they are fully commited, they don't harm people on purpse they just tackle. There is of course a risk. The Jimmy Bullard injury where he dislocated his knee was from a heavy challenge by Scotty Parker. It was a clean tackle but Bullard, who also went in got his knee caught. Bullard came out a few days after the match saying that he doesn't blame Scott Parker in the slgihtest because in his words "he got the ball cleanly" and this guy is just missing a year of his footballing career. It's the same to a lesser extent in France and Italy. Hell there are players in Spain, a country that is more technical than physical, to my knowledge have tough tacklers, Obuina (sp?) the Celta player, just got his first cap for Spain, is a hard tackling midfielder, and I for one would love Arsenal to sign him. You need a hard tackler or 3 to intimidate the opponents, you don't need to hurt them on purpose, just tell them you'll not back down.
I don't watch enough Portugese football, mainly due to the lack of coverage here, but surely there are hard tackling midfielders. And if it were against the rules as you so say, they'd be out of careers by now, or at least in the lower divisions where rules aren't followed as strictly.
Just because someone is injured doesn't meanit's a foul.