Russell was arrested on a charge of bigamy as he stepped from a train at
Waterloo Station on 17 June 1901. Why an action was brought for this rarely prosecuted crime is uncertain. Russell believed that he was prosecuted when, as he related, another nobleman who had acted similarly but was a favourite at Court was not, because he was "an unbeliever and a radical". The Russell family always believed that the earl was prosecuted at the behest of the new king,
Edward VII, who had a chequered past and several mistresses while on the throne, to boost his own reputation for morality. Russell was bailed, and following a hearing at
Bow Street Magistrates' Court on 22 June, he was indicted for bigamy by a
grand jury and
committed for trial. Until the privilege was abolished in 1948, peers and peeresses indicted for treason or felony were tried before the House of Lords, a majority vote deciding the matter. Russell could not have waived trial there had he wanted to, and the verdict of the House of Lords could not be appealed. Such trials were rare: Russell's trial was the first since that of
Lord Cardigan, who was acquitted on a charge of duelling in 1841, the previous trial having been in 1776, and only one trial, resulting in the acquittal of
Lord de Clifford for manslaughter in 1935, followed before the abolition. Russell's trial before the House of Lords took place in the
Royal Gallery of the
Houses of Parliament on 18 July 1901, with some two hundred peers present, including
Lord Salisbury, the prime minister. The
Lords Spiritual who were among Russell's judges were
William Maclagan, the
Archbishop of York and
Randall Davidson, the Bishop of Winchester (later
Archbishop of Canterbury).
Lord Halsbury, the
lord chancellor, presided under the king's commission as
lord high steward. Also present were Mollie Russell, Judge Curler, and the English clergyman who had performed Russell's first marriage. The assembled peers and judges in their robes were deemed "most picturesque" by
The New York Times, which described a "magnificent blaze of color" from the robes of the assembled peers and judges. All the
Lords of Appeal were present to advise the peers on any legal questions that arose, as were eleven other judges. This required the suspension of the courts over which they would have presided that day, and some newspapers questioned the cost of the spectacle, which included the expense of bringing over Curler from Nevada and housing him for two months. When Russell's trial began on 18 July, he was called upon to plead guilty or not guilty, but his counsel interposed, and argued that because the wedding had taken place in America, Russell had not violated the bigamy statute. Lord Halsbury dismissed the point without even requiring the prosecution to respond. Russell then pleaded guilty, and made a statement defending his conduct and stating that no one had been injured thereby, and the lords retired to consider their verdict. The House of Lords had the power to disqualify Russell from sitting there in future unless pardoned, but it did not. On the recommendation of Lord Halsbury, Russell was sentenced to three months at
Holloway Prison. He wrote in his memoirs that the privilege of peers cost him dearly, as he probably would have been sentenced to a token day in prison at the Old Bailey had he been a commoner. Instead, a great sum of money and considerable effort had been expended to provide him with a trial before the Lords, "and it was necessary that the sentence should bear some relation to the fuss made about it." In anticipation of his arrival, a room for favoured prisoners, previously occupied by the journalist
W. T. Stead and by some of the
Jameson raiders, had been prepared for him, where he could have his own food and wine. {{quote box | align = right | width = 24em | salign = right Russell spent part of his time in prison peppering the
home secretary,
Charles Ritchie, with petitions for his early release (which he did not gain) and for better conditions and more privileges (which, mostly, he received). He read through the works of
Shakespeare, twice, and wrote his first book,
Lay Sermons, treating religious and ethical questions from his perspective as an agnostic. His friend, Santayana, was unimpressed with the book, describing it as "the only regrettable consequence" of Russell's incarceration. He was released on 17 October 1901, eleven days before his divorce by Mabel Russell became absolute (George Somerville's divorce of Mollie had become absolute on 24 June). Frank Russell married Mollie according to English law on 31 October 1901. Frank Russell persisted in his view that he had done nothing wrong. In 1911 he approached the prime minister,
H. H. Asquith, asking for a free pardon, and when asked why he deserved it, told Asquith, "Well, the official reason is that I have been a good citizen, for ten years since the offence, and that my conduct is free from any reproach; but if you ask me for the real reason I should say because the conviction was a piece of hypocritical tosh." A free pardon was duly issued by the home secretary,
Winston Churchill. ==Second marriage==