Haha! That is a bit unclear. Yes, I meant "all college level coursework, including college level coursework taken during (not at) high school."
To answer you question more directly, I don't think law schools are actively doing background checks on each applicant they accept, let alone each applicant that applies. If, for whatever reason, the law school does find out that you withheld/slanted any information - be it purposefully or not - you risk not only getting kicked-out/denied from the law school, but getting black listed from the legal profession entirely. Also note that the undergraduate school you graduated from may have the information from your JC. It may not be explicitly stated on your transcript, but if there is even an illusory reference to it (i.e. a line that says "Transfer Credit GPA: 1.3" - UH OH!!!), law schools/LSAC could quickly find out something is up.
Say you did with hold this information and made it through law school - you sneaky ninja you. Although, as I said, I doubt law schools are conducting these background checks, I am sure the bar will conduct basic background checks on you. They will cross reference all this information with your law school application. Any information that is different/odd will raise red flags. At this point, you will have 3+ years of lost work experience, $100k+ worth of debt, a worthless piece of paper that says JD and your name on it, and will be black listed from working in the legal profession. Sad day.
So, if the ethical perspective isn't enough to deter someone, this practical perspective (hopefully) should. Don't lie on your application. Don't omit information. If anything, you want to over disclose information. And if you seriously have questions, ask the law school(s) you are applying to - they will be able to answer these questions in even better detail than any of us.