Here is what ends up frustrating me most about when people end up talking about the 3 uses of the Law. There is only 1 Law. That it. God's Law. The Holy Spirit uses that Law in three different ways - but it is the one and the same Law that is used in different ways.
You cannot preach 1st use, or 2nd use, or 3rd use. You preach the Law -- and the Holy Spirit uses it as He wills. What you think will guide... may curb or it may accuse. What you think will accuse may in fact guide. You are not in control of what the Word does, oh Preacher - you simply preach and the Holy Spirit does the rest.
Now before you get your dander up - let me make a comparison. In the catechism we confess that the Lord's Supper works the forgiveness of sins, life, and salvation.
It's not three Suppers. It's not as though the Supper has three different "parts" that you get to micromanage and control. It's not as though you can say, "Today I will administer the Supper in such a way as to give only Salvation, but not forgiveness and life." No - there is 1 Supper, and it gives three things... or we can talk about what it gives from three different angles.
Likewise - there is only Law... there are not multiple "types" of Law anymore than there are multiple "types" of the Lord's Supper. Now, what does the Law do - well, the Spirit will use it in multiple ways. Just as we can speak of the Supper bringing us multiple things.
But you realize -- in both cases, either Law or Gospel - it's still the Holy Spirit doing everything, right?