"POLITICAL REFORM" is a nice, all-purpose term whose definition - and possible drawbacks - must be found in the details. A good example is the package of election changes proposed by President Carter and Vice President Mondale this week. Some of their recommendations strike us as being sound. These include a constitutional amendment to abolish the archaic electoral college in favor of direct popular election of the President and revision of the Hatch Act.

The Hatch Act is a good example of a well-intentioned law that has become stifling. Mr. Carter proposes enabling most federal employes, except those in acutely sensitive posts, to engage in political activity if they choose. He would also - essentially - maintain protections against political coercion and partican abuse of federal officers. We're not sure whether or how Congress can draft a statute meeting all these goals. But generally we favor the effort to promote both government integrity and individual rights - including the freedom not to take part in politics.

The rest of the Carter-Mondale proposals strike us as being a good deal chancier and more open to objection. We will reserve for the moment comment on his proposal to extend public financing to congressional elections, and idea that is fraught with dangers and complications and one we intend to address separately soon. For now we prefer to take Mr. Carter's recommended improvements in the method of registering voters as an illustration of the way in which the pursuit of unexceptionable democratic values an lead the best-intender reformer into self-defeating results.

The Carter-Mondale plan for election-day registrate on raises questions of the limits of the law as a stimilus to political reform. The plan's purpose is to encourage more citizens to vote. That is a worthy aim - but registration does not seem to be a major barrier any more. Since 1960 the opportunity to vote has been vastly expanded through the Voting Rights Act, the lowering of the voting age to 18, shorter residence requirements and simpler registration systems in many states. And voter participation has been dropping nonetheless. Non-voting is most rife among the young, the less affluent, the less educated and those who lack strong community ties. This is more an indictment of recent politics than a reflection of the registration laws.

That is not to say that polling-place registration isn't worth a broader try. Messrs. Carter and Mondale, however, are not content to recommend this plan to other states. They want to make it a full-fledged federal system program, mandatory in federal elections, strengthened by federal approval of states' voter identification rules, and sweetened by federal grants to the states - with supplements funds for "voter outreach" and other activities. All in all, it's one of those nice-sounding but awful ideas. Anybody can guess what would come next: affirmative action programs for precinct workers, "outreach" demonstration projects, charges that federal funds are being used as walking-around money, and more rules and restrictions and "reforms." And each such step erodes the traditional role of the states and stifles free, competitive political activity.

The problems of the current campaign financing law should have taught us all that government can only do so much to promote better politics. President Carter has had a few glimpses of this himself. Indeed, he now wants to modify the system of public financing of presidential contests in order to revitalize state and local campaigning that involves a national ticket. He also thinks the reporting rules could be simplified. Yet, at the same time, he has proposed this new national-registration program and endorsed public financing for congressional elections. All this suggests to us that Mr. Carter and his allies, in their zeal to improve the political system, are not fully mindful of the fact that at some point the system - sure as death and taxes - starts to choke the politics.