Ethics in government is shaping up as an issue in the 1984 election campaign. As White House counselor Edwin Meese III fights back against critics, Democrats see an opportunity to make political capital of the fact that his financial transactions and other matters are under investigation by the Justice Department. Walter Mondale has accused the Reagan administration of tolerating ''sleaze.'' Gary Hart has assailed the record of ''misconduct'' by administration officials.
Now the Democratic Congressional Campaign Committee has issued a fat packet of material cataloging what it terms a ''long and growing pattern of ethical misconduct by Reagan administration appointees.''
There is a high element of election politics in all this. But the Meese affair has stirred concern in many quarters, including Republican ones, that the Reagan administration has a far poorer record of ethical behavior than the lofty tone of the President's rhetoric suggests.
It is difficult to measure the degree of scandal in the Reagan presidency against previous presidencies, especially pre-Watergate administrations. ''There are no comparable numbers, because the Ethics in Government Act is working to make such things public,'' says Jack Walter, executive director of the National Academy of Public Administration. ''Before 1978 many ethical matters were handled very privately and the press did not have access to information.
''But qualitatively it does seem to be a frequent problem,'' says Mr. Walter, who was head of the Office of Government Ethics under President Carter and early in the Reagan administration.
Other presidencies also have had problems. Harry Truman got into trouble when his military aide accepted a freezer from a manufacturer. Dwight Eisenhower had to get rid of a close aide, Sherman Adams, who accepted a vicuna coat. The Nixon presidency went down in disgrace over the Watergate scandals. And President Carter was hounded by criminal allegations against his economics adviser, Bert Lance.
What distinguishes this administration is that President Reagan himself has not been politically touched by the misdeeds of his aides. He remains curiously immune from criticism - a ''Teflon-coated President,'' as he is now described. But the controversy over his nominee for US attorney general is beginning to generate more news media attention to the broad question of cronyism and favoritism in government.
Not all the instances of ethical misbehavior in the Reagan administration have involved criminal wrongdoing. But questionable actions by more than 40 low- and high-ranking officials in various agencies seem to point to ethical indifference in the administration. Among the more prominent cases:
* National-security adviser Richard Allen resigned in January 1982, after $1, 000 and three watches were discovered in his White House office safe. He said he had intercepted the money from Japanese journalists who were trying to offer it to Nancy Reagan.
* The director of central intelligence, William J. Casey, invested heavily in stock in 1982 before putting his holdings in a ''blind trust,'' as most government officials do in order to avoid charges that they are using inside information for personal gain.
* Deputy Defense Secretary W. Paul Thayer resigned after one year in order to defend himself in an insider trading suit filed by the Securities and Exchange Commission.
* Thomas C. Reed, former deputy assistant to the President for national security, was dismissed after reports that he had made stock profits of more than $400,000 with the help of illegal insider information.
* Charles Z. Wick, head of the United States Information Agency, surreptitiously taped telephone conversations with other government officials and at first denied he had engaged in the practice.
* US Attorney General William French Smith had to give back a $50,000 severance payment from theEarle M. Jorgenson Company.
* EPA chief Anne Burford resigned after congressional probe into alleged favoritism to industry in connection with the agency's toxic waste cleanup program.
* Michael Cardenas, administrator of the Small Business Administration, resigned following investigations of SBA grants. One was to an Albuquerque contractor who was under criminal investigation.
* Max C. Hugel, deputy CIA director for clandestine operations, resigned after being accused of taking part in questionable stock dealings.
* EPA assistant administrator Rita Lavelle was convicted of perjury and obstructing a congressional investigation for covering up her role in an EPA crackdown on a company she used to work for. Some critics attribute such lapses to the ''business ethics'' of people Reagan surrounds himself with. Others see them as a manifestation of a decline in the nation's moral standards.
''It reflects the general loose standards in the country,'' says Amitai Etzioni, a sociologist at George Washington University. In his new book ''Capital Corruption,'' Dr. Etzioni warns that corruption has reached wide proportions in Washington not simply because of misdeeds by individual officials but because of the flow of special-interest money to politicians. He also notes widespread public apathy to ''legalized corruption.''
Says presidential historian Fred I. Greenstein of Princeton University: ''It's hard to conduct a proper mode of government in a society in which a large proportion of relationships are legal but would be suspect in public life.''
Mr. Walker says he believes the administration's ethical problem is not one of having enlisted too many men and women from industry. Countless businessmen have served and are serving government with distinction, he notes. ''It's not a public/private sector thing, but a manifestation of the fact that administration appointees and appointers do not have a respect for the enterprise of government ,'' Walker says.
With respect to nominations for attorney general, Walker points out, it used to be standard for a new appointee to consult with the office of legal counsel in the Justice Department about conflict-of-interest matters. William French Smith did not go through this process.
Viewed historically, scholars say, the trend of ethics in government is generally in a forward direction. There have been periods of egregious scandal and graft followed by periods of reform. The cleanup in the early 20th century, for example, was once such reform wave. The reforms after Watergate were another.
''If you iron out the blips (the periodic lapses by individual officials), the standards in government have steadily gone up,'' says political scientist James Sundquist of the Brookings Institution. ''We have professionalized many jobs that used to be given out on a patronage basis. The civil service has been reformed. Congressional ethics are also vastly better than before.''
President Reagan's style in dealing with charges of wrongdoing has been strongly to back the individual under fire. This has helped convey a sense of Mr. Reagan's loyalty to those who serve him and keeps morale high. But, in the end, those tainted by scandal have ended up leaving.
''Reagan does get rid of them,'' says one observer, ''but gives indication he does not do it willingly. Politically, it is possible he has managed such situations well.''
Reagan's vulnerability on the Meese issue depends on what emerges from the Justice Department investigation and any inquiry by a special prosecutor. Republican political observers suggest that even if Meese is cleared, he may decide not to take the job in order to spare the President political embarrassment in the election.