Barbara Hewson told online magazine Spiked that the move was necessary in the wake of the Jimmy Savile scandal to end the "persecution of old men".
She also said that complainants should no longer receive anonymity.
The NSPCC called her views "outdated and simply ill-informed" and said to hear them "from a highly experienced barrister simply beggars belief".
Her remarks come after a number of high-profile arrests over allegations of historical sexual offences in the wake of the Jimmy Savile scandal.
Among those to have been convicted is former BBC broadcaster Stuart Hall, who admitted 14 charges of indecently assaulting girls, including one aged nine, between 1967 and 1985.
Ms Hewson described Hall's crimes as "low-level misdemeanours" which "ordinarily... would not be prosecuted". I wonder if they seemed like that to the girls he molested?
|Stuart Hall admits indecent assaults|
"What we have here is the manipulation of the British criminal justice system to produce scapegoats on demand. It is a grotesque spectacle," she said.
"It's time to end this prurient charade, which has nothing to do with justice or the public interest."
She argues for an end to complainant anonymity, a strict statute of limitations to prevent prosecutions after a substantial amount of time has passed and a reduction in the age of consent to 13.
She said that "touching a 17-year-old's breast, kissing a 13-year-old, or putting one's hand up a 16-year-old's skirt" are not crimes comparable to gang rapes and murders and "anyone suggesting otherwise has lost touch with reality".
The NSPCC described crimes such as Hall's as "incredibly serious" and said that "to minimise and trivialise the impact of these offences for victims in this way is all but denying that they have in fact suffered abuse at all.
"Any suggestion of lowering the age of consent could put more young people at risk from those who prey on vulnerable young people."
It also argued that complainant anonymity should be maintained and that historical prosecutions should be allowed as "many who are abused are bullied, blackmailed and shamed into staying silent, often well into adulthood".
The Hardwicke chambers, where Ms Hewson works in London, said it dissociated itself from her comments.
In a statement, Hardwicke said: "We are shocked by the views expressed in Barbara Hewson's article in Spiked.
"We did not see or approve the article pre-publication and we completely dissociate ourselves from its content and any related views she may have expressed via social media or any other media outlets."
Also, From England
Faculty of Public Health president Prof John Ashton said society had to accept that about a third of all boys and girls were having sex at 14 or 15.
He said the move would make it easier for 15-year-olds to get sexual health advice from the NHS.
Downing Street said the current age of 16 was in place to protect children and there were "no plans to change it".
Official figures suggest up to a third of teenagers have sex before the age of consent.
Age of consent
Australia: 16 or 17 (depending on territory)
Prof Ashton said lowering the age by a year could "draw a line in the sand" against sex at 14 or younger.
There already is a line in the sand, Professor, what makes you think that by moving it, it will suddenly become effective?