thanks for the awesomely informative answers!
To try to clear up the mud, let’s look at our 5-4 Lawrence hypo again (with Kennedy joining Scalia). You would have:
4 justices saying that sodomy laws targeting homosexual AND heterosexual people are unconstitutional.
4 justices saying that sodomy laws targeting homosexual people are just fine.
1 justice saying that sodomy laws targeting ONLY homosexual people are unconstitutional.
When you do your ciphering and read the opinions, you see that a majority of the Court has held that a sodomy law against only homosexual people is unconstitutional by a majority (5-4). You could then take this and try to craft a law banning sodomy for everyone.
But, as it happened, we had 5 votes saying that banning sodomy for ANYONE is unconstitutional. That prevails, and no new legislative tricks can happen.
Speaking of muddying the waters, see Rapanos v. United States:
Rapanos v. United States - Wikipedia
In a nutshell, the SCOTUS was asked whether wetlands not directly connected or tributary to “navigable waters of the United States” (i.e., deep waterways or the ocean) are regulated by the Clean Water Act.
The SCOTUS produced three opinions. Four said yes, four said no, and one (Kennedy, of course) said that it depends on circumstance. To exceedingly simplify the consequences of the split, the Law of the Land on this issue is now dictated by Kennedy’s minority opinion, because his is the deciding opinion in all aspects of the decision where the the other two opinions are in conflict.