When in doubt, sue.

At least that is the impression you get looking at the latest statistics on the workload in the federal court system.

In 1979, more than 192,000 cases were filed in the district courts. More than 162,000 were civil cases, up 23 percent from the year before and double the number filed 10 years ago.

The 30,000 criminal cases filed were down 10 percent from 1978, reflecting the Justice Department's decision to let state and local prosecutors handle less-complicated cases such as car thefts and gun violations.

But the number of filings with the federal appeals courts is up too, 11 percent, to nearly 22,000.

And the number of pending cases, the backlog that is clogging the federal courts, also continues high: 20,000 appeals, 184,000 civil cases, nearly 15,000 criminal cases.

Maurice Rosenberg, head of the Justice Department's office for improvements in the administration of justice, said there is a general feeling among judicial experts that the delay in settling cases is harmful. "There are many important cases that the courts should decide with reasonable dispatch," he said. "If they are wallowing in this sea of mud, their ability to deal with these important cases certainly is limited.'

He said that at times, judges have so many cases they have to churn out decisions "like stringing beads." The result, Rosenberg feels, is that some judges aren't writing good opinions and their work is becoming more bureaucratic than cerebral.

Rosenberg is quick to point out that numbers alone don't explain the burden on the system. "It's not just the number of trucks, but how heavy they are, that determines how fast the highway wears-down," he said.

For instance, last year prison inmates made 23,000 filings in federal courts, according to Joe Spaniol of the Administrative Office of the United States Courts. "That's the fastest growing part of the caseload," he said.

But other court experts, including former attorney general Griffin B. Bell -- a longtime court of appeals judge -- note that such filings often are found to be frivolous. A complicated antitrust case, on the other hand, can take years to settle.

A chief villain in the continued massive backlog of cases in the federal courts is delay, the experts agree. As Rosenberg noted, attorneys handling the cases are confronted by the "happy coincidence" in most instances of being paid for every minute of painstaking preparation for their clients.

To help break the log jam in the courts, Congress already has given President Carter an unparalleled patronage plum -- the power to appoint 152 new federal judges. But most haven't been on the bench long enough yet to make a dent in the workload.

When he was attorney general, Bell appointed University of Virginia Law professor Daniel Meador to prepare a package of court reform measures he touted in Congress for improving, as he put it, "access to justice."

Part of the idea was to shift the workload, by expanding the authority of federal magistrates to hear some cases, or permit mandatory arbitration of certain civil cases.

The magistrates bill is now law, but the arbitration idea is stalled in Congress.

The proposal that would have the greatest impact on the federal court caseload is the so-called "diversity" bill, which would eliminate the option of letting residents from one state file claims against those from another in federal, rather than state, court. Such cases now make up 22 percent of the federal civil caseload, according to Justice Department figures.

Diversity jurisdiction was allowed in the federal courts to avoid perceived bias by local courts against the out-of-stater. Many experts feel its time has passed, but the professional bar opposes its elimination because it wants a choice of where to file suit.

The fight over the diversity bill has poisoned relations between the House and Senate Judiciary subcommittees that process the court reform bills, some participants feel.

Because the organized bar was caught napping, the diversity bill almost passed the last Congress. But at the last minute, Sen. Dennis DeConcini (D-Ariz), chairman of the Senate Judiciary subcommittee on judicial improvements, withdrew his support and the bill died.

Congressional Quarterly reported recently that relations with the parallel House subcommittee, chaired by Rep. Robert W. Kastenmeier (D-Wis.), have been strained ever since.

Rosenberg's office at the Justice Departments is now in the midst of studying how to attack the more basic underlying twin problems of the backlog in the federal courts: cost and delay.

Rosenberg told The Third Branch, a federal court publication, in January that he felt "the devotion to the billable hour concept" had been partly responsible for the delays and increasing cost of major litigation. He suggested looking for alternatives to the practice of billing by the hour, in hopes of speeding the settlement of cases.

One congressional expert on the caseload problem said he wasn't going to hold his breath waiting for that to happen.