IN SEPARATE OPINIONS last week, two federal judges in Maryland reached similar disturbing - though not surprising - conclusions about prison conditions in the state: They found that at both the Maryland House of Correction and the Maryland Penitentiary, the overcrowding represented cruel and unusual punishment - and therefore was unconstitutional. It is an agonizingly familiar story in this area, where the city government has spent years in court lamely defending the same kinds of horrible conditions at the old D.C. Jail. In one of the Maryland cases, the court has issued a warning much the same as that issued by the judge in the District case; in ordering the absolute elimination of "double-celling" - jamming two inmates in cells of 40 to 44 square feet - U.S. District Judge Alexander Harvey II warned that he might well include "as a last resort the drastic and unwanted measure of ordering the release of certain prisoners."

That's a worrisome prospect, but what all of the judges are saying is simply that there can be no excuse for cruel and unusual punishment in the incarceration of human beings. In the District, the opening of the new jail has taken off the pressure - for a while. But in the city, in Maryland and elsewhere around the nation, the pressures on jails and prisons are fierce. The trouble is, the problems of corrections departments do not usually rank high on the political agendas of mayors or governors - or their constituents, for that matter.

As a result, there are inmates who should be in state prisons who wind up instead in the jails. Jails aren't supposed to be prisons - for prisons are meant to be places where convicted criminals serve their sentences. Instead, convicted murderers, armed robbers and others have been packed into the same ancient warrens alongside people who can't make $100 bail on nonsupport charge or some other lesser offense of which they are presumed to be innocent until proven guilty. In turn, some violent offenders may have been let free because judges have become increasingly reluctant to aggravate conditions of overcrowding.

Maryland's corrections system has been in an awful jam for years. The number of convictions and the lengths of sentences have been increasing faster than the corrections capacity. Many plans for new facilities have been advanced, but nearly every proposal seems to hit the same obstacle: local resistance - the old "anywhere but here" response. So despite efforts by state officials, there is no quick fix in sight for Maryland's detention problem. In both of the latest opinions, the judges noted that Maryland officials had prepared plans to modernize prison facilities and had begun construction of new prisons. But as Judge Harvey noted, scheduled completion date for the construction is 1982, and prisoners "cannot wait for another four years" for improved conditions.

If it takes emergency measures by state officials, judges and the state legislature, so be it. As readers may recall, Marvin Mandel tried unsuccessfully to acquire a mothballed Navy troop carrier to use for work-release prisoners. And Sen. Charles McC. Mathias Jr. (R-Md.) once asked the Army to let the state borrow the Ford Meade stockade. Those proposals may sound a little desperate. They are. But something's got to give. It doesn't help individuals or society to get lawbreakers off the streets only to pack them into tiny cells, for too many of those warehoused human beings will ultimately return to the streets more embittered and more threatening than they ever were.