(FORTUNE Magazine) – As adumbrated in the headline, the news is bad for partisans of rationality in public policy. Herewith glum tidings about the recent adventures of two laws notoriously lacking backing among economists, frequently calumniated in these columns, and occasionally -- but not right now -- looking as though they might actually get repealed. -- Davis-Bacon. Repealing this legislation is no longer considered an original idea, as both the Reagan and Bush administrations attempted for years to do the deed. Their efforts resulted in only one accomplishment worth mentioning: causing ''repeal'' to occur in the Nexis database 683 times within 30 words of ''Davis-Bacon.'' The 1931 statute in question, which requires payment of union wages on government construction projects and adds about $1 billion a year to federal spending, will not go away. Glumly facing this reality, the Bushmen tried hard to water down the requirement by allowing contractors to hire more non-union ''helpers'' to work with union journeymen. Labor Secretary Lynn Martin vouchsafed that this would create jobs, causing union stalwart Tom Harkin of Iowa, chairman of the Senate Appropriations Subcommittee on Labor, to expostulate: ''Jobs are not the issue. Slaves had jobs. The issue is what kind of jobs.'' Just before the election, the Administration finally did succeed -- by threatening a veto -- in preventing the Democrats from writing legislation that would have barred implementation of the helper provision. What will prevent them now is unclear. -- The Delaney clause. One is recurrently surprised to find the clause -- a 1958 attachment to the Food, Drug, and Cosmetic Act -- still lurking on the books. It has had no serious defenders for years, but continues to look invincible because no solon wishes to get tagged as the guy who voted for cancer. Reagan-Bush initiatives against Delaney got nowhere. The law insanely bars all food additives and pesticides if they cause cancer in laboratory animals at any level of tolerance, a standard that precludes use of numerous beneficial additives. To get around the problem of congressional cowardice, the Environmental Protection Agency has tried in recent years to bypass the amendment by invoking a de minimis dodge, under which you could pretend to be in compliance by allowing substances posing ''negligible risks.'' This worked fine until last July, when the Natural Resources Defense Council and other fanatics sued the EPA and won in the Ninth Circuit Court of Appeals. Our own analysis says the fanatics are wrong on the merits but right on the law. Back to square one.