As I recall, the Ten Commandments in the themselves have nothing against abortion(I could be wrong, of course, as I haven't read them in a while), and cover every basic of secular law... so having them above the Courthouse really shouldn't be that much of a problem...
Thou shalt have no other gods before me.
Thats already off putting to anyone of not the Christian faith (non secular)
You shall not make for yourself a carved image
Argueable value and largely irrelevant (non secular)
You shall not take the name of the Lord your God in vain
Happens whenever someone has to take an oath with under god in it when they don't believe, (non secular)
Remember the Sabbath day, to keep it holy.
People work on Sunday's get over it (non secular)
Honor your father and your mother,
Shame child abuse cases happen and child vs parent court cases do happen (Semi-secular, theres no law on it)
You shall not murder.
At number 6 we at last have a secular law (secular)
You shall not commit adultery.
Although morally wrong in society I'm pretty sure there is very little the law has to say on it. (semi secular)
You shall not steal.
The other secular law in the 10 commandments (secular)
You shall not bear false witness against your neighbor.
Remember children, god doesn't want you to tell porkies to your neighbour, few curcumstance it's relevant, court is one of them (Secular)
You shall not covet
Pretty sure Jealously isn't a secular law, (non secular)
So there you have it, 2(3) of the ten commandments have been made into secular law, 2 of them are semi relevant to secular law, and 5 are religious only. Also they do not cover the basic law's because torture and rape is not under the list, and I'm pretty sure the geneva convention and bill of human rights was pretty big on the torture thing.