In most instances, arrests can be made only on authority of a judicial warrant, with the exception of suspects caught in the act of committing crimes. Suspects often are arrested without warrants, but judges tend to overlook this irregularity. Those arrested are required to be brought before an officer of the court as soon as possible, generally within forty-eight hours (ninety-six hours when organized crime is alleged), whereupon their statements are taken and they are informed of the charges against them. Within seventy-two hours of arraignment, the judge must remand the arrested person to prison or release him or her.

Criminal trials in nearly all cases are tried by a judge without a jury. The judge acting alone bases his or her verdict on written statements, depositions, and expert opinion, although in some instances oral testimony is presented. Defendants have access to counsel, and those unable to afford legal fees can be assigned public defenders. The quality of pro bono counsel is often inferior. The accused and his or her lawyer do not always meet before trial, and the lawyer may not appear at the important sentencing stage. The right to a public trial is guaranteed, as is the right to confront one's accusers and to be provided with a translator if the accused's native language is not Spanish. Under the constitution, the court must hand down a sentence within four months of arrest for crimes carrying a maximum sentence of two years or less, and within one year for crimes with longer sentences.

The entire process--the time for a trial, sentencing, and appeals--often requires a year or more. According to Amnesty International, a large number of persons charged with crimes have been held far beyond the constitutional limits for their detention. The long trial process and the detention of those who cannot qualify for or make bail are major causes of crowded prison conditions.

The penal code stipulates a range of sentences for each offense. Sentences tend to be short, in most cases not longer than seven years. The actual time of incarceration is usually three-fifths of the sentence, assuming good behavior. Those sentenced for less than five years may avoid further time in jail by payment of a bond. Prison Conditions

The penal system consists of both federal and state correctional institutions. The largest federal prison is the penitentiary for the Federal District. The Federal District also sends prisoners to four detention centers, sixteen smaller jails, and a women's jail. Each state has its own penitentiary. There are, in addition, more than 2,000 municipal jails. As of the end of 1993, nearly 95,000 inmates were in Mexican prisons; almost half were persons still awaiting trial or sentencing.

Overcrowding of prisons is chronic. Mistreatment of prisoners, the lack of trained guards, and inadequate sanitary facilities compound the problem. The United States Department of State's country reports on human rights practices for 1992 and 1993 state that an entrenched system of corruption undermines prison authority and contributes to abuses. Authority frequently is exercised by prisoners, displacing prison officials. Violent confrontations, often linked to drug trafficking, are common between rival prison groups.

Mexican prisons also exhibit some humane qualities. In 1971 conjugal visiting rights were established for male prisoners and later extended to females. Prisoners held at the penal colony on the Islas Tres Marías off the coast of Nayarit are permitted to bring their entire families to live temporarily. Women are permitted to keep children under five years of age with them.

Based on interviews at a smaller state prison, United States penologist William V. Wilkinson found in 1990 that serious overcrowding, lack of privacy, and poor prison diets were the most common complaints. Wilkinson found no deliberate mistreatment of inmates. The prison fare generally was supplemented by food supplied by prisoners' families or purchased from outside. Prisoners with money could buy items such as television sets and sports equipment. Through bribery, prisoners could be assigned to highly prized individual cells, where even air conditioners were permitted.

A major building program by the CNDH added 800 prison spaces in 1993 and 1994. In 1991 Mexico's only maximum security facility, Almoloya de Juárez, was completed. Major drug traffickers were transferred to it from other prisons. The prison's 408 individual cells are watched by closed-circuit television and the most modern technical and physical security equipment. Violence in prisons is a constant problem as a result of overcrowding, lack of security, and the mixing of male and female prisoners and of accused and sentenced criminals.

Imprisonment of peasants, often for growing marijuana, puts a heavy demand on the system. Through the efforts of CNDH, a program of early release and parole benefited 1,000 people incarcerated on charges of growing marijuana in 1993.

Under the terms of the 1977 Prisoner Transfer Treaty between the United States and Mexico, United States prisoners in Mexican jails and Mexican prisoners in United States jails may choose to serve their sentences in their home countries. An extradition treaty between the United States and Mexico took effect in January 1980. It requires the mutual recognition of a crime as defined by the laws of each nation. Because of the extensive processing required under extradition requests, however, informal cooperation has developed among police on both sides of the border. Suspected criminals who flee to the neighboring country to escape apprehension routinely are turned over without formal proceedings to police in the country where the crime was committed.

Noncompliance with the Prisoner Transfer Treaty has occasionally created friction between the United States and Mexico. The United States strongly criticized Mexico's decision in 1988 to release William Morales, a leader of the Puerto Rican Armed National Liberation Front, who was wanted for a series of bombings in New York in 1978. Mexico rejected a United States extradition request even though a Mexican court had found Morales extraditable. Washington objected particularly to the initial Mexican characterization of Morales as a "political fighter."

The death penalty has not been applied in Mexico since 1929, when the assassin of president-elect Obregón was executed. The federal death penalty was abolished under the Federal Penal Code of 1930, and by 1975 all state codes also had eliminated the death penalty. The military, however, still holds certain offenses as punishable by death, including insubordination with violence causing the death of a superior officer, certain kinds of looting, offenses against military honor, and treason.