Why are black males ages twenty-five to twenty-nine more likely to be in jail than are Whites and Hispanics?

Famed black author William Du Bois offered a viewpoint early in the 20th century that continues to have some validity today:

There are no reliable statistics to which one can safely appeal to measure exactly the growth of crime among the emancipated slaves. About seventy per cent of all prisoners in the South are black; this, however, is in part explained by the fact that accused Negroes are still easily convicted and get long sentences, while whites still continue to escape the penalty of many crimes even among themselves. And yet allowing for all this, there can be no reasonable doubt but that there has arisen in the South since the [civil] war a class of black criminals, loafers, and ne'er-do-wells who are a menace to their fellows, both black and white.

Today Hispanics are in the prison population in about 1.5 times their proportion in the general population, and blacks are in prison in about 3 times their proportion. There is no general consensus why this is true. Wikipedia has a good article on this.