MADISON, Wis. — The Wisconsin Supreme Court adopted rules yesterday allowing judges to hear cases involving their biggest campaign contributors, siding with business interests and rejecting calls for reform.

Voting 4-3, the court approved rules that say donations by groups and individuals to judges and independent spending to help them get elected do not by themselves require judges to step aside from cases.

The additions to the judicial code of conduct were proposed by two powerful Wisconsin business groups, the Wisconsin Realtors Association and Wisconsin Manufacturers and Commerce, and adopted without a single change.

Justices Patience Roggensack and Annette Ziegler said the rules would prevent litigants from trying to force judges off cases simply because they received legal donations. Justice David Prosser said it would protect justices from attacks by those who unfairly suggest campaign money influences decisions.

Their decision could have national importance because Wisconsin is one of the first states to reconsider rules for judicial recusal following a U.S. Supreme Court ruling in June. In that case, Caperton v. Massey, the Court ruled that elected judges must step aside from cases when large campaign contributions from interested parties create the appearance of bias.

Wisconsin’s code had been silent on campaign donations, saying only that judges should withdraw from cases when a reasonable observer would question their fairness. That general rule will still apply.

The court rejected proposals that would have required judges to step aside if they received donations from parties or their lawyers above a certain threshold, such as $1,000 or $10,000.

Those rules were proposed by retired Justice William Bablitch and the League of Women Voters, who said reform was necessary to improve public confidence in the court’s integrity as spending on judicial campaigns skyrockets.

Bablitch had warned the court not to adopt the business-backed rules.

“They want to keep a system that has worked for them but that has not worked for the average litigant,” he said. “That’s the worst thing you could do.”

The push for reform came after Ziegler and Michael Gableman won election in 2007 and 2008 in races marked by big spending by outside groups. The manufacturers group alone spent an estimated $4 million to help Ziegler and Gableman combined, according to the Wisconsin Democracy Campaign.

Since her election, Ziegler has been reprimanded for sitting on cases involving a bank where her husband was a paid director while she was a Washington County judge. Gableman is fighting a complaint that alleges he violated the judicial code by lying in a campaign ad about his opponent’s record.

Gableman and Ziegler joined Prosser and Roggensack in adopting the rules yesterday.

“I’ve gone through the experience of members of the court being subjected to attacks without any justification,” Prosser said. “I’m sorry, I’ve had it. It is time to address a true crisis that has been created, not by people on the court but people outside the court.”

Chief Justice Shirley Abrahamson and Justices Patrick Crooks and Ann Walsh Bradley voted against the rules, which they said ignored public concerns about the influence of campaign spending on decisions.

“This is the present law and people seem dissatisfied with it, so we should be doing something different,” Abrahamson said.