In recent months, Public Television has been replaying Robert Kennedy’s famous remark from his ill-fated 1968 presidential campaign: “We are all brothers.”

Of course, the late Mr. Kennedy’s sentiments apply to the 350 people arrested and detained as illegal immigrants on March 6 at the plant of Michael Bianco Inc. — a New Bedford company that makes safety vests for the U.S. government. Whether or not many of these fellow human beings will be found to have entered the United States illegally, they are our brothers and sisters.

But — here’s the rub that many don’t get — the federal agents, Homeland Security officials and police who carried out the raid are also our brothers and sisters. They were doing their jobs, carrying out lawful orders, and enforcing the laws of the United States.

At the moment it is mainly the authorities who are being demonized by political demagogues and by those who defend illegal aliens in any situation. (The defenders, of course, are rarely people who have been in a position to lose jobs or otherwise suffer from the more problematic aspects of the illegal-immigration flood into the United States.)

Many local television stations and newspapers love sob stories that lack rigorous analysis, or the context of history, law or any other embarrassing elements of realism. They prefer highly simplistic drama. And there were plenty of tears shed by those arrested on March 6. Such politicians as Ted Kennedy and John Kerry were on the scene, weakly saying, in effect, that immigration laws should be enforced, sort of, but . . . but, oh, can we count the Democratic votes that a replay of the 1986 federal amnesty (which turned out to be a joke in legal terms) would create! Joining them in spirit are those (mostly Republican) businesspeople who just adore having an ever-growing ocean of cheap labor.

A non-demonological analysis would look first at the raid itself, then at the truly germane issue: the national interest.

Of the raid itself, one wonders what the point was of a grand show of force. If exits were duly guarded, what was to prevent authorities from calmly questioning employees about their immigration status, and then detaining, at least temporarily, those the evidence called for?

Then there was “the race to the airport.” The suspected illegals were whisked to such far-away places as Harlingen — the very southernmost point in Texas — on the Rio Grande — a convenient spot from which to send illegals to Central America from whence they came. But the law can swiftly lose its majesty when its enforcement at least appears to be carried out in panic and confusion.

On the broad issue of the national interest, this newspaper is clear: The “come-on-up” culture of the last 21 years needs to be changed, though the corrupt and sometimes dictatorial governments and the social and economic elites that run much of Latin America love and encourage the flood of illegal aliens into the U.S.: They use it as a pressure release for the socio-economic problems caused in large part by crummy governments south of the Rio Grande.

Illegal immigration lowers wages of low- and middle-income Americans, takes jobs from unskilled Americans, strains municipal budgets, social services and public education, and adds disproportionately to the prison population.

Yes, these are our brothers and sisters. But that doesn’t mean they have the right, ahead of every single legal immigrant, to be in the United States.

In any event, the immigration issue is ultimately going to revolve to a large extent around how crowded a country we’re willing to be. The U.S. population unofficially passed 300 million late last year. If the 13.1-percent-per-decade rate of growth continues unchecked, we will reach 500 million in about 2049, and 1 billion in about 2095.

The tears of young mothers caught by surprise in a raid make good television. But someone — apparently it won’t be Ted Kennedy or John Kerry — needs to contemplate what kind of environment and what kind of society the United States would have with a population of a billion people.