The 1978 Maryland General Assembly concluded its work last night after effectively dismantling legislation designed to curb political corruption in the state.

The ethics legislation, which was supposed to tighten laws prohibiting conflicts of interest by state officials, was to have been an election year showpiece for the legislature and the administration of Acting Gov. Blair Lee III. It was introduced after years of political scandal in Maryland, including the conviction last August of Gov. Marvin Mandel, and a plea by Lee to help erase the state's "absolutely intolerable" image of corruption.

Opponents in the legislature succeeded, however in watering down the ethics package through amendments. They then tacked on so many new provisions in the final days that it risked being "talked to death" as the session neared its mandatory conclusion at midnight last night.

The legislature did enact other significant measures yesterday, including a bill at stopping the increasingly common practice of "child snatching" by estranged parents in custody battles. The bill makes it a crime for someone who did not have custody of a child to take it from the parent who had been awarded custody. The police, for the first time, could enter such cases and make arrests.

Another bill enacted yesterday would require the state of Maryland to purchase 10 percent of its goods and services from minority businesses.

As debate in both chambers continued late into the evening on these and other, more minor issues, legislators who wandered into the halls for a rest could be heard congratulating themselves and each other for the session's accomplishements.

It was a year when the legislative process could well have dissolved into disarray, in part because of the absence of suspended Gov. Mandel - who had until recent years exercised firm control over the legislative process - and in part because of the upcoming fall elections.

The legislators managed to reach important compromises on some of the most important and intractable issues before them.

Chief among these was the problem or rising property tax assessments, which had homeowners across the state angrily demanding relief from their legislators.

Before the session was two-thirds complete, this major issue seemed resolved. The complaints and suggestions of legislators with widely differing viewpoints were combined in a seven-bill package of property tax relief legislation which included a measure legislation returning about $30 million in property tax credits to lower-income homeowners.

The compromise package, which was worked out after prolonged negotiations between Acting Gov. and a half dozen legislative leaders, was considered one of the most impressive achievements of the session.

At the same time, legislative leaders were also working to ensure that the most emotional issues facing the legislature would be disposed of well before the hectic closing hours.

They succeeded in this endeavor. Before the session was half over, legislation had been enacted restoring the death penalty in Maryland for specific types of murder.

Then, two weeks before the close of the legislative session, the General Assembly scratched out a compromise on an even more emotional question: whether the state's Medicaid funds should be used to pay for abortions for poor women.

After the House and Senate arrived at widely differing conclusions - the Senate approving unsrestricted abortion funding and the House calling for severe restrictions - a conference committee worked out a compromise which would allow abortion funding if one doctor certified that a continuation of pregnancy would endanger the mother's health or if the pregnancy were a result of rape or incest or if the fetus was deformed.

A final emotion-laden issue, the legalization of the controversial cancer drug laetrile, was resolved late last week when the legislature sent Lee a bill allowing physicians in the state to prescribe laetrile for cancer patients.

The Assembly did defeat overwhelmingly a measure that would have restructured the pension system that covers $50,000 state employes and teachers throughout Maryland.

The bill's proponents predicted that the cost of present system would, in 10 or 20 years' time, overwhelm the state budget and precipitate a fiscal crisis.

However legislators, particularly in the House of Delegates, were obviously more receptive to the pleas of teachers' union lobbyist who said the new system was unfair and that the resolution of the complex pension system problems could wait until another year when the legislators could approve revisions more to the teachers' and employes' liking.

Election year concerns were evident during the early phases of this year's ethics bill as legislators initially tripped over each other to show scandal-weary Marylanders they were serious about regulating the conduct of public officials.

When Lee revealed plans in his state-of-the-state message to introduce an ethics bill, his gubernatorial rival Stenis H. Hoyer hurriedly put his name on aseparate measure. To insure that his bill would prevail, Hoyer, the senate president, attracted 32 cosponsors, including several senators traditionally cool to reform legislation.

But the early session interest in inform gradually dissolved as the ethics bill moved through the legislative process. The Senate killed the Lee bill and passed the Hoyer measure after a few weakening amendments and the defection of several of the bill's original sponsors.

The House continued to whittle away at the bill yesterday, deleting such key features as a blanket prohibition on gifts to public officials from lobbyist and persons doing business with the state. It killed a provision requiring public officials to disclose all business interests.

The original bill was designed to replaced the current hodge-podge of ethics laws with statutes prohibiting conflicts of interest by legislatures and top state officials. They are now regulated by in-house rules that are not legally binding.

Legislators also attempted to deal this year with some of the other lingering concerns raised by the political corruption trial of Mandel.

One of these was a question of the governor's salary, which, at $25,000 a year, was the lowest gubernatorial salary in the country. This year, the legislature enacted a measure raising that salary to $60,000, thus making Maryland's governor the fourth highest paid in the country.

After raising the governor's salary, the legislators moved to raise their own pay. Their course on this was more circuitous however; they took advantage of a quirk in a state law, and manage to give themselves a series of raises which will take them from their present $12,500 salary up $18,000 for the four years while appearing to vote against any raise.