       The sentencing disputes are a legacy of the crack
epidemic of the mid-1980s. Then, Congress set stiff mandatory
prison terms based on the amount of the drug in the hands of a
seller. One gram of crack cocaine was treated as though it were
equal to 100 grams of powder cocaine.  Five grams of crack
cocaine (less than one-fifth of an ounce) called for five years
in prison, according to the 1986 law, as did 500 grams of powder
cocaine. Fifty or more grams of crack meant 10 years in prison,
as did 5,000 grams of powder cocaine. This 100-1 ratio was
blamed for sending an extraordinary number of African Americans
to federal prisons for long terms.  In a rare bipartisan move,
Congress agreed in 2010 to pull back and adjust the punishments
for crack offenses. The Fair Sentencing Act set 28 grams of
crack as the trigger for a five-year prison term, and 280 grams
for a 10-year term. But it did not say what should happen to
people charged but not yet sentenced.  The Supreme Court will
hear the appeals of two men f