When drug testing is mandated, employers almost always follow the SAMHSA (Substance Abuse and Mental Health Services Administration) guidelines because it puts them on solid legal ground. Typically, there is an overlap between testing guidelines and accepted cutoff levels for drugs and drug metabolites in confirmatory testing and screening.
Because THC is widely recognized as being responsible for marijuana's psychoactivity and euphoria, a routine urine drug screen for marijuana seeks to detect it and its main metabolite, THC-COOH. If the screen in positive, a confirmatory GC/MS (Gas Chromatography/Mass Spectrometry) test is performed to verify the positive urine screen. This test is specific to detecting THC-COOH.
Fortunately, the urine drug screen for THC-COOH is known to have very little cross-reactivity to other cannabinoids that are not intoxicating, such as CBD (cannabidiol), CBG (cannabigerol), CBN (cannabinol), and others. This is good news for "normal" consumers of CBD/hemp oil.
That said, individuals using unusually large doses of a cannabinoid-rich hemp oil product (above 1000-2000 mg of hemp oil daily) could theoretically test positive during the initial urinary screen. Although VERY RARE, the urine screen in these cases would likely represent a "false positive" due to other non-THC metabolites or compounds. When this is the case, the confirmatory GC/MS test would be negative, since CBD and other cannabinoids will not be detected by the more accurate (and specific) GC/MS screen.
Keep in mind that most of the high-quality, reliable CBD-rich hemp oil products contain much less THC than marijuana. For example, hemp contains anywhere from 1/10th to 1/300th of the THC concentration found in marijuana. An individual consuming 1000-2000 mg per day of hemp oil would thus consume approximately 3-6 mg of THC. This exceedingly high dose may result in detection of positive urine screen in up to 11% to 23% of assays.
On the other hand, there is some data demonstrating that at daily doses of 0.5mg of THC from 3-5 servings of most commercial CBD-rich hemp oil products, the positive urine screen rate is less than 0.2%. Again, most servings of typical high-quality, high-purity CBD-based hemp oil products contain well below 0.1mg of THC and therefore have over 400-600 times less THC than marijuana products.
What does all this mean? Put simply, a consumer who uses a high-quality, scientifically vetted hemp-based product at the standard serving size is highly unlikely to test positive for THC and/or THC-COOH. However, it's important to be cognizant that extremely high doses may result in a positive urine screen (that would be subsequently shown to be false via GC/MS). Ultimately, consumers need to be fully informed of the specific regulations posed by their employers and adjust their consumption of cannabinoid products accordingly.