The judge in former U.S. President Donald Trump's upcoming trial over his handling of classified documents made two key errors in a June trial, one of which violated a fundamental constitutional right of the defendant and could have invalidated the proceedings, according to legal experts and a court transcript.

Florida-based U.S. District Judge Aileen Cannon closed jury selection for the trial of an Alabama man - accused by federal prosecutors of running a website with images of child sex abuse - to the defendant's family and the general public, a trial transcript obtained by Reuters showed. A defendant's right to a public trial is enshrined in the U.S. Constitution's Sixth Amendment.

Cannon, a 42-year-old former federal prosecutor appointed by Trump to the bench in 2020 late in his presidency, also neglected to swear in the prospective jury pool - an obligatory procedure in which people who may serve on the panel pledge to tell the truth during the selection process. This error forced Cannon to re-start jury selection before the trial ended abruptly with defendant William Spearman pleading guilty as part of an agreement with prosecutors.