Cause and effect? Possible, but not clear

As he introduced his new running mate, Democratic presidential candidate Barack Obama lauded Delaware Sen. Joe Biden's legislative achievements, highlighting one that matters to a key voting group: women. "Joe Biden wrote the Violence Against Women Act, so every woman would have a place to turn for support," Obama said in Springfield, Ill. "The rate of domestic violence went down dramatically, and countless women got a second chance at life."

As chairman of the Senate Judiciary Committee, Biden shepherded a major crime bill through Congress in 1993 and 1994. One key piece was the Violence Against Women Act, a bill that Biden had been pushing for years. VAWA, as it's known in Washington, included provisions that authorized $1.6-billion in grants for programs to fight domestic violence, established a toll-free national hotline on family violence and created federal penalties for interstate stalking or domestic abuse. Congress has since renewed it twice.

Since VAWA became law, domestic violence rates have dropped dramatically, according to the U.S. Justice Department. In 1993, 5.8 out of every 1,000 people age 12 or older reported being victims of nonfatal intimate partner violence. By 2005, that rate had dropped to 2.3 per 1,000, a decline that fits Obama's description: "went down dramatically."

Okay, so both of Obama's statements are true. Biden wrote an anti-domestic violence law, and domestic violence rates dropped dramatically.

But did one cause the other? Although Obama doesn't say it directly, that's the clear implication in his statement, and that's where things get a bit murkier. As we discussed back in 2007, when Biden was gunning for the top spot on the Democratic ticket, figuring out the reasons for changes in crime statistics can be tricky. Multiple factors, including economic prosperity and demographic changes, contributed to an overall decline in violent crime throughout the 1990s and into this decade.

"There's still generally no consensus about why any crime in general has dropped," Shannan Catalano, author of the Justice Department study, told the Associated Press in 2006. "It's safe to say it's more than one factor that went into it."

In fact, the same federal crime statistics that show domestic violence rates dropping, also show the trends were similar in overall violent crime and in murder rates. A case can be made that domestic violence rates might have dropped without passage of the VAWA.

Featured Fact-check

Fred Thompson

stated on August 20, 2007 in an ABC radio commentary.

"... study after study has shown that the death penalty deters murders."

There are, however, some solid reasons to think Biden's law made a difference. A study by the University of Arkansas, for instance, concluded in 2000 that the law's increased funding for civil legal assistance for victims contributed to the decline. Though that study also said economic and demographic factors mattered.

Obama never said the law caused all of the decrease, but he implied it, so we will rate this statement Mostly True.