STRATFORD, Conn.--Just about every one of us is vitally affected by politics and the powers attendant upon it. This was true in ancient times and has remained so ever since. To explore the matter for his Elizabethan audiences, Shakespeare drew on Roman history for his Titus Andronicus. Julius Caesar, Antony and Cleopatra, and Coriolanus.

Although Julius Caesar is not the greatest of these plays, it is by far the best known, probably because of the enormous fascination Caesar has exerted over the ages. In medieval and Renaissance times Caesar was the only Roman to be honored with a place among the Nine Worthies; in Michael Hart's new book The 100, which is an all-time ranking of the most influential persons in world history, Caesar comes out No. 65.

This summer the American Shakespeare Theatre is offering Julius Caesar for the fifth time in its history. This time the director, Gerald Freedman, spurred by the work's universal applicability, opted to set the play in our own era, in order, as he said, "to place some mutual perspective on the events of Julius Caesar and on the events of our day."

The attraction of presenting Shakespeare in modern dress dates from the productions of Sir Barry Jackson, starting with his Hamlet of 1925. The earliest modern-dress Caesar apparently was the anti-Fascist one with which Orson Welles, at age 22, inaugurated his Mercury Theatre in 1937 (the previous year he had mounted an all-Negro Macbeth set in the voodoo world of Haiti). In 1939 Henry Cass put the play in Mussolini's Italy. Donald Wolfit, Minos Volanakis, Michael Croft and others have since updated this drama.

Freedman here has not settled on a specific city, but he has chosen to make his Caesar a Latin American caudillo, who enjoys wearing his military uniform with its gold braid and rows of campaign service ribbons. Our century is familiar with such personages: Peron in Argentina, Estrada Cabrera and Ubico in Guatemala, Gomez and Perez Jimenez in Venezuela, Vargas in Brazil, Hernandez Martinez in El Salvador, Ibanez in Chile, Stroessner in Paraguay.

Like Caesar, a number of these Latin leaders met their deaths through assassination: Castillo Armas in Guatemala, Trujillo in the Dominican Republic, and--within eight years--Carranza, Pancho Villa and Obregon in Mexico. Dictatorship brings with it danger, as today's headlines about Nicaragua's Gen. Somoza Debayle indicate. It is worth recalling that Somoza's father obtained his dictatorial power by assassinating Gen. Sandino, only to be assassinated himself some years later.

I am not prone to enthusiasm about modernized Shakespeare, mainly because it tends to serve gimmick-happy directors without serving the playwright; such was the case with several of the American Shakespeare Theatre's early efforts. But it is possible to throw fresh light on the text through modern-dress productions, as Michael Kahn did here with his Love's Labour's Lost in 1968. Freedman's Caesar takes numerous risks, and for the most part succeeds surprisingly well.

Freedman's concept has been aided by Robin Wagner's settings and Michael J. Cesario's costumes. Wagner, who did the sets for Kahn's 1973 Caesar here, has this time designed a huge three-dimensional grid of steel rods. Walls, glass panels and movable furniture slide in and out as required. The effect suggests a technological society surrounded by steel and glass; the only color is gray.

The costumes reflect today's world. Some of the young citizens carry portable radios. The conspirator Cinna comes in from the rainstorm with a wet umbrella; he carries a businessman's attache case, which when opened turns out to contain knives for the murder (one recalls the old-time gangsters who used to conceal machine guns inside violin cases). The conspirators wear three-piece business suits. The conspiracy is hatched in a cocktail lounge; Artemidorus, the rhetoric teacher, who will try to warn Caesar of the plot, has become a journalist who eavesdrops and takes notes in a reporter's pad. The Soothsayer is a blind man hawking copies of an astrology magazine. Mark Antony, on his first appearance, wears a jogging suit and running shoes. In his domestic scene with his wife, Caesar is attired in pajamas, bathrobe and slippers. Cicero appropriately carries a book, and Casca nervously smokes cigarettes. You get the idea.

Freedman's modernization does not stop here, however. He has turned his production into a multi-media event by employing photographs, film clips and closed-circuit television. From time to time five large screens drop down. On each is projected a different view--now a movie clip, now a still. There are motorcades, massed throngs, and, in the military half of the play, battle scenes and fire-bombings. In the background is a special soundtape collage put together by Mark Dichter, who holds degrees from M.I.T. and Columbia's film department.

This is not the first time that Caesar and cinema have met. Of the roughly 400 silent films adapted from Shakespeare's plays between 1899 and 1929, there are ten versions of Caesar, the first being a French effort of 1907. In the half century since 1929, about 50 sound films have been made, including three of Caesar, all American. The straightforward 1953 version, directed by Joseph Mankiewicz--with James Mason's Brutus, John Gielgud's Cassius. Marlon Brando's Antony, and the late Louis Calhern's Caesar--remains the only excellent Shakespearean film ever done in our country (and few people know that its off-camera crowd roars in the stadium were specially recorded by a huge throng at a baseball game).

And what of Freedman's performers? Once we get through an ill-spoken opening scene and the major characters appear, most of the cast perform admirably. Much of what they have to do here is far from easy, and obviously called for a good deal of meticulous drilling.

Marcus Brutus, the play's longest role, is in the hands of Kenneth Haigh. In 1956 Haigh burst on the scene as the original Angry Young Man in Osborne's Look Back in Anger. Now, in 1979 (the year he turns 47, 49 or 50, depending on what source you credit), Haigh is the Stoic Middle-Aged Man. Clearly at home in Shakespeare's language, Haigh speaks with cool conviction and command, and a feeling for the verse rhythms.

That Brutus keeps misgivings bottled up inside is apparent from the way Haigh rubs his forehead in private as though suffering a headache. It is characteristic of his distaste for panache that, when committed to war, he alone among the commanders wears unadorned fatigues--no ribbons, no insignia of rank.

In the second-longest role of Cassius, Brutus' brother-in-law who originates the murder plot, a bearded Harris Yulin makes his position more plausible and less villainous than we usually see--and perhaps it should be said that there are no thorough villains in this play, except for the gang that lynches a poor poet merely for having the same name as one of the conspirators.