Redknapp, tipped to become the next England manager, denies allegations relating to $295,000 paid into a secret Monaco bank account named after his bulldog during his time in charge of Portsmouth.
Defence lawyer John Kelsey-Fry said the prosecution was relying on "primarily despicable" evidence gathered by reporter Rob Beasley from the now defunct News of the World tabloid to support its case that Redknapp was receiving football-related bonuses on which he should have paid tax.
"I do not shrink from suggesting to you it is repugnant to all our basic instincts of fairness in the criminal justice process," Kelsey-Fry said, Britain's Press Association reported.
Referring to interviews carried out by Beasley, Kelsey-Fry said: "They saw a great story, all's fair in love and war at the News of the World."
Redknapp has been on trial at Southwark Crown Court in London with former Portsmouth chairman Milan Mandaric, who also denies wrongdoing over two payments made to Redknapp.
The two men have said the payments were for investments outside of the game.
Redknapp was manager of Portsmouth from 2002 to 2004 and then 2005 to 2008 before joining Tottenham. Mandaric remains involved with football as chairman of League One team Sheffield Wednesday.
Judge Anthony Leonard is expected to sum up the case on Tuesday before the jury is sent out to consider its verdict.
Media tycoon Rupert Murdoch closed the News of the World last July in a scandal over phone hacking after it was disclosed the paper's reporters had intercepted the voicemail of a murdered schoolgirl.
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