I'm not sure what the data looks like for your reference on black vs. white drug use since the original data isn't there.
Some data indicates there is a 23% higher level of drug use among blacks than whites [1, Table 1.19B]. That would explain _some_ of the higher arrest rates of blacks for drug crimes.
Some data indicates there is a 23% higher level of drug use among blacks than whites
My quote was "whites and blacks are known to use use and sell at about the same rates" - your link shows 8.7% of whites use drugs vs 10.0% of blacks in the past month, and 15.9% of whites used drugs vs 18.7 in the past year (and when looking at lifetime use, that usage flips) - I think "about the same rates" is a fair characterization of that data.
When we're talking about a 20% difference in arrest rates, if the difference between drug use rates is >10% I don't think it's fair to characterize that as "about the same".
Some data indicates there is a 23% higher level of drug use among blacks than whites [1, Table 1.19B]. That would explain _some_ of the higher arrest rates of blacks for drug crimes.
[1]http://www.samhsa.gov/data/NSDUH/2012SummNatFindDetTables/De...