Three trials involving Congressional committee power to ask questions about an individual's associations or beliefs will begin or resume today.

Leon J. Kamin's trial for contempt of Congress will reopen for three hours today in the Boston Federal Building and then recess again until next Monday.

Meanwhile, Marcus Singer, once an instructor here, and now a zoology professor at Cornell, will go on trial in 'New York today for refusing to answer questions asked by the House Un-American Activities Committee about a "Marxist Study Group" at the University during the war.

In Washington today, lawyers for author Harvey O'Connor and the prosecution will present to a trial judge written arguments about Senator Joseph McCarthy's right to ask whether O'Connor was a Communist. O'Connor's trial, which, like Kamin's, has no jury, recessed three weeks ago after evidence was complete. The judge asked for the written briefs before giving his verdict.

The Monday resumption of Kamin's trial is unusual, as Judge Bailey Aldrich '28 normally tries no cases on Mondays, but instead hears motions.

The government will present several witnesses today although Senator Charles E. Potter of Michigan, originally expected to appear, will not be present.