Dynamite 1;
I'm sure the carrier you leased onto provided a copy of the "Green Safety Regs Handbook" (see 49CFR, Part 382). This is the material that contains the actual DOT Regulations. Along with that book, you most likely received a "Contractor or Driver" Manual from that carrier. The Contractor Manual most likely states that the carrier has adopted the DOT regs as a "company policy".
As far as when randoms are conducted - the regulations do NOT stipulate when the randoms are conducted. In fact the regs even speak about Motor Carriers conducting daily, weekly, monthly quarterly and so on. It makes sense to conduct radoms more frequently if you are a large carier having thousands of drivers. Smaller carriers will do less frequently.
You are correct that the DOT reviews the testing rates, but only in previous years. At the beginning of each year, the DOT does their own "random selection" of carriers to submit Annual Staistical Reports of their company testing results - the of tests taken, how many were pre-employment, how many randoms, how many post-accident... It also asks for the number of positives in each category. This is where they obtain information that would enable them to change the required testing rates. The rates have NOT changed since the regs were implemented in 1995.
I sincerely hope this helps you better understand the required testing.
P.S. BernieH48 - I too find it hard to believe your husband was selected randomly for 15 tests in one year, though it could happen. With luck like that perhaps he should invest in some lottery tickets!
Thanks,
HotFr8Recruiter