A federal magistrate in Denver ruled yesterday that Gary Hart's 1988 presidential campaign has no legal obligation to pay the debts Hart ran up in his 1984 race, a decision that could prove both a fiscal and a legal boon to Hart's current drive for the White House.

Magistrate Richard B. Harvey of the U.S. District Court rejected efforts by two of Hart's 1984 creditors to garnishee a $100,000 certificate of deposit held by a bank here in the name of Hart's 1988 campaign. The ruling frees the $100,000 -- plus $1,440 in accrued interest -- for Hart's immediate use, and may give him a precedent to invoke in contesting two new claims filed here this week by 1984 creditors.

"By my ruling," Harvey wrote, "there is a judicial determination that {Hart's 1988 campaign committee} is not legally obligated to pay the bills of Americans With Hart." Americans With Hart was the legal name of Hart's 1984 presidential organization. Harvey said the two campaign organizations are distinct corporate and legal entities, and therefore not liable for each other's debts.

Hart's renewed 1988 campaign has about $53,000 in debts and aides have said he plans to use the $100,000 freed up by yesterday's decision to pay them.

Yesterday's ruling was the second Hart court victory on the point. Last July, a federal judge in Los Angeles ruled that "creditors of Americans With Hart are not entitled to levy upon the assets or funds raised by Hart '88."

The Los Angeles and Denver decisions both dealt with money raised through individual contributions to Hart's 1988 campaign -- not with federal matching funds. That may distinguish the two cases from those filed here this week, in which 1984 Hart creditors asked a court to attach federal matching funds due Hart's 1988 campaign.

Bernard Schneider, the Los Angeles lawyer working on the debt issue for Hart, said the campaign will argue that the Los Angeles and Denver decisions should control in the Washington cases as well, because they establish that the two Hart campaigns are legally independent of each other.

Hart's legal victory today involved garnishment actions brought by Tri-State Envelope, a Beltsville, Md., concern, and Semper-Moser Associates, a Venice, Calif., direct-mail firm. Semper-Moser also was the unsuccessful plaintiff in the Los Angeles case. Representatives of the firms could not be reached immediately for comment last night.

While Hart's 1988 campaign finances were boosted by the Denver court ruling yesterday, more than $2 million in debts, unpaid bank loans and unapproved debt settlements remain from the 1984 race.

The most recent campaign report for Americans With Hart Inc. at the Federal Election Commission shows the 1984 campaign owed $1.1 million to creditors, was carrying nearly $942,000 in settlements that had not been approved by the FEC, and owed the National Bank of Washington $504,000.

The 1984 debt issue has become a focus of attention again because Hart has qualified to receive federal matching funds for his renewed 1988 race and old creditors want him to transfer an expected $1 million in such funds to his 1984 committee to pay them off.

Hart asked the FEC for permission to do this before he dropped out of the race last May. But the issue was considered moot then, because he dropped out before becoming eligible for the public funding.

Since getting back in the race, Hart and his aides have given conflicting answers about whether they would again seek an FEC opinion. Hart's campaign manager, Susan Casey, did not return a reporter's call yesterday.

At the same time Semper-Moser, the most aggressive creditor from 1984, has been chasing the candidate from one courthouse to the next trying to get paid. The firm also has been negotiating with Hart's new campaign on a novel fund-raising idea to retire the old debt.

The proposal is that Semper-Moser, which is owed nearly $163,000, would advance Hart's 1984 campaign committee funds to finance a direct-mail appeal to donors and then take enough of the proceeds to get repaid. James Turner, Washington attorney for Semper-Moser, said the firm is willing to go back to 1988 Hart contributors in a special solicitation to see if they would be willing to help pay off the old debt.

The company, which bought radio air time for Hart ads in five western states, has sued Hart in Washington, D.C., Denver and Los Angeles in an effort to get its money.

Some of the $942,000 in debt settlements the Hart campaign made with other vendors were for as little as 10 cents on the dollar and date back to mid-1986. The FEC has not yet approved them and it is not clear whether this is because of a routine matter or whether the commission staff is investigating some of the agreements.

The law says the FEC must be convinced the creditors made "commercially reasonable" efforts to collect the debt or it might be considered an illegal contribution.

For example, a Portsmouth, Va., printing company, Group III Communications, did more than $886,000 in business with Hart that year and was owed $421,184 at the end of the campaign. It signed a debt settlement agreement -- one of those still to be approved -- last March for $42,118, 10 percent of what it was owed.

Special correspondent Susan Kelleher in Denver contributed to this report.