You know, we had very high levels of incarceration before Holder ever came into office. US incarceration rates took off like a rocket in 1980 and have been heading up ever since, and you don't change 30+ years of momentum on a dime.
Also, a very large percentage of people in federal prison are non-violent drug offenders.
Exactly the sort of situation he is proposing to change, as mentioned in the news story.
"you don't change 30+ years of momentum on a dime"
Holder has been in office since early 2009; 4.5 years is a pretty significant fraction of 30 years. Why is he suddenly interested in this issue now? My guess is that the administration is desperate to divert attention away from the NSA's domestic spying and the NSA/DEA intelligence sharing.
This isn't the first thing they've done about it. Getting rid of the sentencing disparity between crack and powder cocaine was a pretty big issue, plus there's been the financial crisis to deal with. The DoJ is severely underfunded.
Also, a very large percentage of people in federal prison are non-violent drug offenders.
Exactly the sort of situation he is proposing to change, as mentioned in the news story.