Based on my (imperfect) understanding of the "law," it means that my partnership should bid up to the same level as the number of trumps. For instance, with four trumps over my partner's five card major, I could raise his bid to three.

But I was taught to use a combination of trumps and points. Thus, we'd want to bid four spades with 26 points and eight trumps, or with 23 points and nine trumps, or with 20 points and ten trumps. So why the "law?'

Apparently, the opponents' (theoretical) trump suit also figures into this equation. How do I count for their "trumps?" And once I've done so, how do I combine their trumps and mine into a "law" calculation? Why would I do this anyway?