For aspiring political journalists, the Capitol Hill publication Roll Call has long been the place to cut your teeth covering Congress, make your mark, and then jump to a mainstream newspaper. But now there’s another path: Several prominent Roll Call graduates, now in the prime of their career, have come full circle, returning to their roots in niche publications. Jim VandeHei, executive editor and cofounder of the everything-politics Politico, worked for Roll Call in the 1990s before heading to The Washington Post. Susan Glasser, executive editor of Foreign Policy, worked her way up from intern to top editor at Roll Call in the 1990s before her own stint at the Post. And Mary Jacoby, who joined Roll Call in 1989 and went on to write for The Wall Street Journal, is moving her own niche startup, Main Justice, into what she hopes will be a profitable new phase.

Washington is a perfect home for online niche publications: Specialized content can be produced with relatively low overhead and then sold to readers hungry for the high-stakes news. Jacoby’s site, which is free (for now), is trying to capitalize on this concept. Her reporters obsessively cover the Department of Justice, the agency at the intersection of politics, policy, and the law. Corporate interests, lawyers, (small-p) politicos, and government employees all have a stake. The site’s target audience is lawyers at DOJ and the broader Washington legal community, which has its own set of political and corporate clients.

Main Justice offers a mix of specialized data (like an interactive chart tracking all U.S. attorneys), event-driven stories (like a new staff hire), and insider trend stories, like a piece on how shuffled portraits of former attorneys general signal power shifts in the agency. They also run expert takes on important legal topics of the moment.

“This idea of focusing on the inside workings of government — we all learned this at Roll Call, and we learned how addictive it is to people inside government,” Jacoby told me. “Now it’s liberating, in a way, that newspapers have dissolved, because we can go back to writing inside baseball. Our readers love it. We love it. And there’s actually money to be made in it becuase it’s specialized information.”

Main Justice launched in April 2009 as a blog Jacoby envisioned running as a solo operation. It quickly took on a life of its own — which she says she wishes she had seen coming much sooner. She picked up venture capital, and now she she has a staff of nine reporters and editors, including former New York Times DOJ reporter David Johnston, who is joining as a partner, as well as reporters from Legal Times, American Lawyer, and Bloomberg.

Her audience is targeted and dedicated. About 25 percent of the site’s 700,000 monthly pageviews come from readers on DOJ computers. About 9,000 users have registered for the site. (After three clicks, the site requires it.)

Now that she has an audience, Jacoby’s next step is to launch spinoff sites around Main Justice, focused on specific legal issues. The first site is expected to launch in July, focusing solely on the Foreign Corrupt Practices Act, the international anti-bribery law. Her next site will focus on the False Claims Act. Legal actions around these laws are picking up, making them both of interest to readers, and potential advertisers, like law firms. These sites won’t be free: she’ll charge users $1,200 annually to access each, with discounts for subscriptions to more than one site, and corporate access capped at $30,000.

Jacoby is also wading into the world of events. Her first, scheduled for June, is a breakfast discussion about mergers featuring Richard Feinstein of the FTC Bureau of Competition. Ticket price: $65. The law firm O’Melveny & Myers is serving as a sponsor, and the session could count toward the continuing legal education credits required of Virginia lawyers.

“It’s clear to us that most of the revenue will come from subscriptions and events,” Jacoby told me. “We’re working now to parse out the legal-practice-specific stories and stick them behind our paywalls. We’ll continue to run information on the Department of Justice — that will stay on the open site.”

Over the last year, Jacoby says she’s spoken with a variety of parties interested in a formal relationship with Main Justice, including The Washington Post Co. and the National Journal Group. But she says she is glad she took the advice of several venture capitalists and media consultant Alan Mutter, who urged her to figure out her business plan and pare down ideas before entering into agreements with outside groups. “There were a lot of people coming out of the woodwork on this and I really didn’t know what the business was, and I didn’t want to commit to anything,” she explained. “Now I know what the business is. We’re securing more money to do this launch of the other sites.”

For now, Jacoby says she sees little in the way of competition. There’s no other outlet dedicated so exclusively to the DOJ. Meanwhile, newspapers have rolled back their coverage of agencies, including DOJ, in recent years. Bloomberg’s new venture, BGov, a site covering the intersection of business and government with a budget of $100 million and 40 to 50 editorial-side staff, would likely tread on similar turf. But Jacoby is not concerned, saying her background in niche news makes her well-situated to maintain her audience.

“I grew up at Roll Call and there was always CQ,” she told me. “And they did separate things. CQ was very data driven. I think not everybody knows how to write these stories that insiders really want to read. It’s not second nature to people.”