The Utah Supreme Court has upheld the constitutionality of the Subpoena Powers Act, reversing a portion of a lower-court decision on a case involving the investigation by the Utah attorney general's office of Utah Power & Light Co.

The decision, released Friday with one justice's dissenting opinion, was labeled a victory by Associate Deputy Attorney General Paul Warner, who called the act crucial to prosecuting white-collar crime.The Subpoena Powers Act was passed by the Legislature in 1971 as an alternative to impaneling a state grand jury, which is costly and difficult. The act gives the attorney general's office and county attorneys the power to subpoena witnesses, grant immunity and conduct investigations in secret with limited judicial supervision.

The Supreme Court, however, did agree with the 7th District Court that the act was unconstitutionally applied by the attorney general's office in its investigation of the utility's security contracts. That point was conceded by the attorney general's office during its appeal.

But Warner said he did not expect the decision to affect the 1985 bribery and racketeering convictions of four men, including a former UP&L security chief, that resulted from the investigation.

Warner said the case was prosecuted without using evidence gathered through the use of the Subpoena Powers Act unless it was corroborated through other sources. The convictions were upheld last month by the Utah Court of Appeals.

UP&L officials and employees who had been issued subpoenas related to the investigation authorized in 1983 by the 7th District Court claimed the Subpoena Powers Act was unconstitutional. In part, their argument was that the act did not protect them against self-incrimination since they were not required to be told whether they were targets of an investigation.

All the subpoenas, except one issued to Emery Mining Corp., were eventually withdrawn by the attorney general's office. Emery Mining, which then operated UP&L's Utah coal mines, successfully fought the subpoena in district court, where the act was declared unconstitutional in September 1984.

While an appeal was pending before the Supreme Court, Warner said the attorney general's office continued to use the act to conduct investigations into white-collar crimes out of necessity.

"Without subpoena power, it just absolutely ties our hands in our ability to get the kind of documentation we need to put together a white-collar criminal case," Warner said. "In white-collar crime, a paper trail is the name of the game so many times."

He acknowledged that continuing to use the act while its constitutionality was being reviewed was a risk but said the only alternative was to avoid prosecuting white-collar crimes.

Assistant Attorney General Stanley Olsen estimated the number of white-collar crimes investigated during the three years the case was pending before the Supreme Court at between 20 and 40.

Now, those cases will be reviewed according to the guidelines for implementing the act outlined in the Supreme Court decision to make sure they comply, Warner said.

Assistant Attorney General Robert Parrish said that most of the guidelines have been followed since the issue of constitutionality was first raised, including those aimed at protecting witnesses against self-incrimination.