What do you have
 

Last night girls HS V game. Late in first half home is attacking. Defender slides in from side/front with studs up. Not real high. No contact. Gets all ball. What, if anything would you call?

As described nothing other and "great tackle, thanks for keeping your feet ball height." I say something similar to let opponent know I saw the play and to reinforce to all what I am looking at to evaluate foul vs fair tackle.

It depends upon the level of aggression that the players have been accepting and the referee has been allowing in the match. I've seen this judged a legal play, a dangerous play (IFK awarded), and even a cautionable offense.

This is one of those situations in which one has to have a feel for the game.

I'd agree with this to a certain extent. Sounds like it was a tackle conducted with poor technique, but likely ok.

There was a comment by one of the announcers in yesterday's UEFA ch leg match about this. He said something similar to: it seems that now anytime that you get the studs up, you are going to get a card or at least give up the foul even though you get the ball.

I can tell you that the instruction at the top levels of play is to really crack down on this type of challenge.

If you saw the first game of the MLS double-header on ESPN2 last Thursday, you saw such a challenge that made contact with the opponent in the 6th minute of play and the result was a red.