Many societies which did not have the ten commandments outlawed murder, theft, etc. The Romans had the most impact on our basic laws as they established them throughout Europe and th subsequently English law greatly influence statutes in the US.
It may be arguable whether the judge can post the commandments, but it is clear that they are not the basis for our laws.
How is "it" clear?
Paragraphs upon paragraphs could be cut and pasted dealing with laws, both modern and ancient. I do not see where prove (or attempt to defend) your assertion, other than making the statement above. You could have added: "So it shall written, so it shall be done" to your words, but it does not make it so.
Internet searches are wonderful things. I was helping my eldest daughter tonight on ancient Egypt--and her eyes were wide with all the information available these days. Research that used to require hours in a library is now at our fingertips.
Placing the words "ten commandments" and "basis for law" into Yahoo or any search engine yields many sites. I found it interesting that the one site that agrees with you (that the 10 Commandments are not basis for laws) was written by the ACLU.
This site presents a more balanced view contains quite a good analysis on the subject. Note that this paper was a lecture on the subject first published in 1908.