New guidelines approved by the U.S. Sentencing Commission on Thursday will mean shorter terms for roughly 70 percent of federal drug offenders. The adjustments will reduce mandatory minimums for offenses that don't involve violence or firearms. Over the past few years, public-opinion polls have shown a shift toward both legalization and treatment rather than prison for drug possession. “We have given careful consideration to public safety in making this decision today and will continue to monitor drug sentences to determine whether any additional modifications are needed,” said chairwoman Patti B. Saris, the chief U.S. district judge in Massachusetts. The new guidelines, which Attorney General Eric Holder testified in favor of, will go into effect Nov. 1 unless Congress votes them down.