U.S. Supreme Court Justice John Paul Stevens retired in June, but he left behind freshly minted decisions that will extend his legacy in day-to-day court cases for years to come.

The Court term that just ended produced an unusually large number of cases that have had nearly instant impact in courtrooms and on practitioners across the country.

Citizens United v. FEC has already produced campaign finance rulings that are on their way back to the high court on appeal. Skilling v. U.S., issued June 24, has already gotten media mogul Conrad Black out of jail on bail and may spring former Enron executive Jeffrey Skilling as well.

Other key business cases, including Stolt-Nielsen v. AnimalFeeds International Corp. and Morrison v. National Australia Bank, are also being cited in new and pending cases. McDonald v. Chicago and Bilski v. Kappos, both issued on the final day of the term June 28, are launching new litigation over firearm regulations and patent eligibility, respectively.

But two decisions that got fewer headlines when they were announced are also producing a broad ripple effect in courtrooms, and both were written by Stevens: Padilla v. Kentucky and Carachuri-Rosendo v. Holder. In Padilla, the Court ruled that a lawyer’s failure to warn an immigrant client about the consequences of a plea agreement on possible deportation amounts to ineffective assistance of counsel. And in Carachuri-Rosendo, the Court sided with immigrants in revising the way minor drug offenses are calculated for deciding whether alien offenders should be deported.

The Padilla case in particular is being cited in much broader contexts than the case itself. The obligation of lawyers to advise clients about collateral consequences of plea bargains well beyond immigration issues — from pension benefits to housing — is being tested in the aftermath of Padilla. Judges have already issued conflicting rulings on the retroactive effect of the decision.

“The Court left open what the rule would be for other consequences, like parole and sex-offender status, so a lot of cases are being filed,” said Stephen Kinnaird, a partner in Paul, Hastings, Janofsky & Walker’s Washington office who argued and won the Padilla case.

“This may be the most important ‘right to counsel’ case since Gideon v. Wainwright,” said Washington solo practitioner Margaret Love, who has written extensively about collateral consequences. “It’s a case where you pull a little string and things begin to unravel. It’s a gift from Justice Stevens that will keep on giving.”

OUT WITH A BANG

And that may be just how Stevens wanted it, says Ohio State University Moritz College of Law professor Doug Berman, author of the Sentencing Law and Policy blog. “When he drafted pro-defendant rulings, Justice Stevens made an effort to use language that was expansive, in this case beyond the immigration context,” Berman said. “The decision has gotten the criminal defense bar not only excited but trying to operationalize it. It’s not the end of the doctrine, but the start.”

One example of Stevens’ broad wording came toward the end of Padilla, and it’s easy to envision it being used in a wide range of cases: “It is our responsibility under the Constitution to ensure that no criminal defendant — whether a citizen or not — is left to the ‘mercies of incompetent counsel,’ ” Stevens wrote.

In the other Stevens deportation case, Carachuri-Rosendo, the Court unanimously rejected the government’s method of adding up prior minor drug-possession cases to amount to an aggravated felony that would trigger deportation.

The decision directly affects hundreds of immigrants facing deportation nationwide, said Chuck Roth, director of litigation for the National Immigrant Justice Center. Several cases that were pending at the Supreme Court have already been sent back to lower courts for a fresh look.

In addition, Roth said, “there are other areas where we can imagine the case will be helpful” as immigrants battle deportation before and after it occurs.

Between Carachuri-Rosendo and Padilla, Roth said, “Justice Stevens certainly went out with a bang from our perspective.”

OPEN FOR BUSINESS

The Court’s 2009-10 term also produced decisions by other justices that have been quickly invoked to aid business defendants, both individuals and corporations.

Skilling sharply narrowed the scope of the “honest services” fraud statute that federal prosecutors have used to pursue corporate executives and public officials in recent years. As soon as the decision restricting the law to bribes and kickbacks came down on June 24, defendants including former Illinois Gov. Rod Blagojevich have tried to use it to their advantage, with mixed success.

“Some cases will fall under Skilling,” said Deputy U.S. Solicitor General Michael Dreeben at The National Law Journal‘s recent review of the last term. “Other cases will be able to be re-characterized as kickbacks or bribes because of the underlying facts or maybe even as money or property. So the long-term impact of the decision in a negative sense for upholding prosecutions is unknown.”

Class action defendants have already begun to benefit from the high court’s recent decisions in Stolt-Nielsen and Morrison.

The Stolt-Nielsen decision said class actions can be submitted to arbitration only when both parties have clearly agreed to it, not when arbitration clauses are vague or silent on the subject. Because of rules regarding appeals, corporate defendants often oppose arbitration of class action disputes, even though they often prefer resolving individual disputes through arbitration.

“The decision is beginning to roll through the circuits and the lower courts,” said Gerald Maatman Jr., a partner at Seyfarth Shaw in Chicago. He just won a post-Stolt-Nielsen case in the U.S. District Court for the Southern District of New York for Sterling Jewelers, which was fighting arbitration in a class action brought by current and former employees claiming workplace discrimination. The ruling by Judge Jed Rakoff appears to be the first applying the Supreme Court ruling beyond Stolt-Nielsen‘s antitrust context. “Stolt-Nielsen is going to be the focal point and pivotal point in arbitration clause construction cases for years to come,” Maatman said.

The Morrison ruling is also shaping up as a significant tool for foreign businesses facing securities litigation. In that case, the Court shut the door on so-called “foreign-cubed” securities fraud litigation brought in U.S. courts by a class of foreign investors against foreign companies involving securities traded on foreign exchanges.

In the wake of the June 24 decision, a federal judge has already narrowed a suit against Credit Suisse, and Vivendi cited Morrison in seeking an end to securities litigation it faces.

“It’s hard to imagine a case that will have as much direct and immediate impact on large existing litigations,” Wachtell, Lipton, Rosen & Katz partner George Conway told Bloomberg News. “It wipes out an entire species of class action litigation.”

GAME-CHANGER?

The Citizens United case, perhaps the biggest case of last term, has also reverberated in new and pending challenges to federal and state campaign laws, said Institute for Justice lawyer Steven Simpson. By a 5-4 vote, the Court said a provision of the McCain-Feingold law barring corporations and unions from direct expenditures in campaigns violated their First Amendment speech rights.

Late last month, Simpson filed a petition with the Supreme Court in SpeechNow.org v. FEC, citing Citizens United throughout. The petition urged the Court to apply the ruling to unincorporated so-called “527″ groups, and strike down legal requirements that such groups form regulated political action committees. The U.S. Court of Appeals for the D.C. Circuit upheld the PAC requirements, though it struck down limits on contributions. Under Citizens United, Simpson argues, the PAC rules should also fall.

The decision will also be helpful in challenges to restrictions on party expenditures, on other aspects of McCain-Feingold and on how much disclosure Congress can require, Simpson said.

Citizens United is hugely important, a potential game-changer,” Simpson said. “How far does Citizens United go in relieving speakers of the burden of campaign finance laws?”

Tony Mauro can be contacted at tmauro@alm.com.