ALMOST ALL of the 125,000 Cubans who came to this country in the 1980 Mariel boat lift must be happy that an immigration agreement negotiated between the U.S. and Cuban governments three years ago will be reinstated. Now normal immigration can be resumed, families will be reunited, and thousands of political prisoners in Fidel Castro's jails will be allowed to leave for the United States. But a couple of thousand of the Mariel immigrants are obviously outraged -- they have been rioting -- because the agreement means that many of them will be sent home. These are the so-called hard-core "excludables" who would never have been admitted to the United States under normal circumstances and who would have been deported long ago if their native country had agreed to accept them.

Thousands of the Mariel Cubans readily admitted upon arrival in this country that they were convicts. These individuals were initially detained, but over the years almost all were released into the community. Only 210 of the most dangerous felons have been held in custody the whole time. Some of those released, however, and some who were not detained initially, have been convicted of crimes here in the United States. This would normally result in deportation, but because of the collapse of normal relations with Cuba, these offenders have been held after completing their sentences so that they could be sent home eventually.

There are now some 3,700 of these people in custody, and their crimes range from fraud to drug trafficking and murder. The total of all excludable aliens now in custody is thus close to 4,000, and most of them don't want to go home. But each of these individuals has had his case personally reviewed. The rights of the group have been thoroughly litigated, and U.S. courts have held that the procedures followed were constitutional. This country has no obligation to keep alien lawbreakers, least of all those who have killed, taken hostages or destroyed or damaged federal facilities this week. In an effort to quell the rioting, Attorney General Edwin Meese has agreed to suspend deportations temporarily while each case gets another review, an arrangement that is more than fair. But it would be very wrong to agree to reward this crowd, which has shown nothing but contempt for the law.

The numbers demonstrate that the vast majority of Cuban refugees in this country have become contributing members of society. All but 210 of the 125,000 Mariel group have had a chance to live in the community and prove themselves. Those who became serious criminals deserve no special privilege