In Washington, the stars may be aligning for “comprehensive immigration reform.” Barack Obama and the Democrats sense an opportunity to prevail where past administrations and Congresses have failed. Republicans hope to improve their share of the Hispanic vote and follow Marco Rubio to the promised land.

But is it good policy? Congress passed and Ronald Reagan signed an explicit amnesty in 1986. To qualify, illegal immigrants needed to pay a fine, learn English, and to have lived in the United States for a certain period of time. This was balanced with employer sanctions and new enforcement measures.

Under this law, some 2.7 million immigrants were legalized. Four years later, George H.W. Bush signed legislation increasing legal immigration by 40 percent. The policy mix envisioned by the president and the Gang of Eight has been tried before.

Much of the promised enforcement never materialized. Illegal immigration surged, by one estimate increasing 44 percent between 1987 when the amnesty took effect and 1989 at the height of the legalizations. By the middle of this past decade, legal immigration was running nearly double what it was in the mid-1980s and the illegal immigrant population swelled to between 12 and 20 million.

The federal government approved nearly 90 percent of the 1.3 million agricultural workers who sought amnesty under the 1986 law despite detecting fraud in close to a third of the applications. Overtaxed immigration bureaucrats are not likely to fare better with a much larger applicant pool.

One of the selling points of the Gang of Eight framework is that it promises to frontload the enforcement, although the provisional legal status would be granted to eligible applicants immediately. But how hard would be it be to get Homeland Security Secretary Janet Napolitano to certify a secure border? Even if border security metrics are genuinely met, 40 percent of unauthorized immigrants enter legally and overstay.

The larger problem of conditional amnesty is that if the conditions have real teeth, they are administratively unworkable and contain disincentives to apply. More often, they prove to be window dressing. The coalition that will pass comprehensive legislation includes many lawmakers who oppose strong enforcement measures.

Here’s a prediction, based on past experience with the 1986 amnesty and the 1996 Illegal Immigration Reform and Immigrant Responsibility Act: even if many of the concessions to enforcement-first congressmen survive the negotiations process and make it into the final bill, there will be a concerted attempt to erode them as soon as the bill is passed.

Others point to the progress that has been made in reducing illegal immigration. The investment in border security and interior enforcement has increased. There are more fences and border patrol agents. The government is now believed to have effective control of 57 percent of the U.S. border. While the sluggish American economy has caused many illegal immigrants to go home—the unemployment rate is now lower in Mexico than in the U.S.—improved enforcement is credited with about half the drop.

But this enforcement is of recent vintage. After the defeat of the last serious amnesty attempt, the Bush administration concluded that stepped up enforcement was a prerequisite for winning the necessary political support for its immigration-policy objectives. The Obama administration continued this pattern, claiming record deportations.

In the years prior to that, however, enforcement was practically nonexistent. According to one study, audits on employers of illegal immigrants declined 77 percent from fiscal 1990 to 2003. Warnings to audited employers dropped 62 percent. Final notices declaring intent to fine businesses hiring illegal workers decreased 82 percent. The amount of fines assessed dropped by more than half, to just $1.2 million, from the 1996 fiscal year to 1999 alone.

Why declare “Mission Accomplished” after just seven years of real enforcement, which appears to be working? We could continue to decrease unlawful entries and gradually reduce the illegal immigrant population by attrition. Then we could assess country’s progress and then perhaps contemplate a legalization program.

After all, there are still 12.3 million unemployed Americans. Nearly 14 percent of blacks and just under 10 percent of Hispanics were officially unemployed in January.

But Democrats and Republicans in the nation’s capital see a bonanza of votes waiting for them if they succumb to temptation to Do Something. They say they want to put the immigration issue behind us, but we have heard that before.

W. James Antle III is editor of the Daily Caller News Foundation and a contributing editor to The American Conservative. Follow @jimantle