Laws in all 50 states permitting people to carry concealed firearms in public have been connected to a rise in violent crimes, according to a new report from researchers at Stanford and Johns Hopkins universities. 

The report, published in September and issued as a National Bureau of Economic Research Working Paper last week, adds to a series of studies over the last decade tending to discredit the "more guns, less crime" hypothesis, which argues that right-to-carry laws serve as crime deterrents by allowing ordinary Americans to better protect themselves. 

The new findings suggest that right-to-carry laws are "associated with substantially higher rates" of aggravated assault, rape and robbery, Stanford law professor John J. Donohue III, one of the study’s three authors, explained in a press release on Friday.  Stanford law student Abhay Aneja and Johns Hopkins doctoral student Alexandria Zhang co-authored the report. 

Among violent crimes, the most significant increase came in aggravated assault, which may have risen by nearly 33 percent, according to the report.  The researchers also found that from 1999 to 2010, murder rates rose in eight states that adopted right-to-carry laws. 

In 2012, there were nearly 9,000 firearm homicides in the United States.  A year earlier, more than 21 percent of an estimated 751,131 aggravated assaults in the nation were committed with firearms. 

A decade ago, the National Research Council found "no credible evidence" associating concealed-carry laws with either a drop or a rise in violent crimes.  It cited weak research models and a lack of sufficient data at the time. 

While the NRC panel relied on county-level crime data from 1977 to 2000, the latest report used data from 1979 to 2010, covering an additional 10 years in which right-to-carry laws expanded and adding a net six more years of county and state records.