Friday's annual March for Life will bring thousands of anti-abortion protesters to the Supreme Court, marking this week's 40th anniversary of the justices' Roe v. Wade decision that legalized abortion nationwide. The event underscores the continuing intensity of a debate that has spawned well-financed lobbies on both sides at the federal and state level. 

Although the 113th Congress has been in session less than a month, the issue of abortion already is on the docket. A search using Sunlight Foundation's Scout, which allows users to track issues in Congress, the 50 state legislatures and the Federal Register, shows that three bills were introduced in the very first days of January.

On Jan. 3 — the first day of this session of Congress — Rep. Paul Broun, R-Ga., introduced the Sanctity of Human Life Act along with 17 other Republican co-sponsors. The bill's purpose is to "provide that human life shall be deemed to begin with fertilization" — which would effectively outlaw abortion.  

Two other bills mentioning abortion that were introduced in early January appear to be identical, but introduced by different members of Congress. On Jan. 3, Rep. Marsha Blackburn, R-Tenn., proposed the Title X Abortion Provider Prohibition Act, which seeks cut federal funding available for abortion providers. The next day, another Tennessee Republican, the more junior Rep. Diane Black, introduced the same bill with 23 co-sponsors. The number of co-sponsors has since grown to 165.

Both measures revive legislation pushed unsuccessfully in past Congresses. The Title X Abortion Provider Prohibition Act originally was proposed in 2007 by then-Rep. Mike Pence, R-Ind., who just left the House to become governor of his state. 

Redefining at what point human life begins has been a core effort of pro-life advocates for many years. This will mark Broun's third attempt to pass the Sanctity of Human Life Act. The bill also bears a striking resemblance to a bill from former Rep. Ron Paul, R-Texas, the Sanctity of Life Act, which also sought to redefine the human life. As with the Sanctity of Human Life Act, Paul introduced the legislation a number of times and also borrowed from its predecessor, the 1995 Sanctity of Life Act, introduced by Rep. Steve Stockman, another Texas Republican who just returned to Congress this year after a 16-year hiatus.

A range of groups on both sides of the abortion debate lobbied both on the Pence bill and the Broun bill when they were last introduced. Among the major players in the abortion debate, Planned Parenthood spent a total of $2.4 million lobbying during the last session of Congress. Meanwhile, the conservative groups arguing on the other side —Traditional Values Coalition, Right to Life and the James Dobson-founded Family Research Council — spent a little more than $1 million combined in the same period. 

Other prominent groups that lobbied on the Abortion Provider Prohibition Act include the AARP, Christian Coalition, People for the American Way and NARAL Pro-Choice America. 

Abortion-focused groups also spend heavily on campaigns and campaign-style advertising to press their views on the issue:

• American Values just released a new video (seen below) that makes an emotional case against abortion; Sunlight unsuccessfully tried to contact the group to learn whether this signals the launch of a television advertising campaign. American Values is headed by Gary Bauer, a prominent GOP social conservative. He is a former president of the Family Research Council and senior vice president of Focus on the Family, both of which have long histories of campaign finance and lobbying activity. He also heads the Campaign for Working Families PAC, which spent $1.4 million in contributions and independent expenditures. 
• Planned Parenthood donated more than $1.1 million to politicians during the 2012 cycle, and its affiliates Planned Parenthood Action Fund and super PAC Planned Parenthood Votes spent a combined $11.9 million to bolster candidates who favor abortion rights. According to Sunlight's analysis of outside spenders' return on investment, more than 98 percent of the expenditures in the general election supported winning candidates. 
• Emily's List, which makes the election of women who favor abortion rights a top priority, donated $3.5 million to Democratic women, and was the top donor for 10 of the new members of Congress. Women Vote!, the super PAC arm of Emily's List, made $7.8 million in independent expenditures with an 80 percent success rate. 
• Susan B. Anthony List, the anti-abortion movement's response to Emily's List, spent $1.7 million donating to politicians, and another $1.5 million on independent expenditures. The groups' return on investment for its independent expenditures was just less than six percent. 
• National Right to Life PAC and National Right to Life Victory Fund spent a combined $3.4 million in independent expenditures supporting pro-life candidates, though with a much lower success rate. The PAC had a 24 percent return on investment, and the Victory Fund just eight percent. Right to Life made $235,000 in campaign donations in the last election cycle. 

While their success rate has not been good on the federal level, opponents of abortion have been chipping away at abortion rights on the state level: 135 laws restricting abortions were enacted by state lawmakers during the last two years, according to the Guttmacher Institute. 

This despite the fact that, according to Sunlight's Influence Explorer, Planned Parenthood and its affiliates contributed $850,000 to politicians running for state office, to state ballot measures and other state political organizations. Right to Life affiliates donated just one-tenth of that amount.

In Arizona, abortion opponents has a particularly successful run last year. The state enacted legislation in April requiring an ultrasound before an abortion, prohibiting lawsuits if doctors fail to provide information that might have led to an abortion and banning abortions 18 weeks postfertilization, among others. The following month, Arizona also enacted legislation limiting family planning funding for organizations that provide abortions. 

To get up-to-date information about legislation and regulations relating to abortion, subscribe to alerts from Sunlight's Scout. 

(Photo credit: Eric Martin and Rick Johnson/Wikimedia Commons)