A teenager accused of sending millions of e-mails to his employer has been cleared because UK laws do not make a crime of what he did.
Many firms are being bombarded with thousands of e-mail messages
The magistrate's written ruling said the teenager's alleged actions did not break the Computer Misuse Act.
He ruled that crashing an e-mail server with five million messages did not break statutes in the 1990 act.
Research reveals many firms regularly face similar e-mail attacks by angry consumers or malicious hackers.
The teenage defendant in the case, who cannot be named for legal reasons, was charged under Section Three of the Computer Misuse Act which criminalises unauthorised access to or modification of computer systems.
But in his written ruling, District Judge Kenneth Grant of Wimbledon Magistrates Court said that although a lot of e-mails were sent, they could not be said to have caused unauthorised changes as defined by the act.
He added that this meant that so-called denial of service attacks were not illegal under the current act.
The ruling meant that the defendant was not called to the witness box to answer the charges and walked free of the court.
Research by security firm Inty carried out in September has found that about 20 e-mail based denial of service attacks are being launched every month. One high profile victim was Greater Manchester Police which during an attack was being hit by 2,000 messages per hour.
Detailed on the ZDNet UK news site, the resolution of the case is widely seen as another blow for the UK's outdated Computer Misuse Act.
Earlier this year the influential All Party Internet Group of MPs called for it to be overhauled and updated to cover the novel crimes the net is being used to perform.
"A denial of service or 'e-mail bomb' attack could cost an organisation millions in downtime and be even more devastating than a traditional virus attack," said Soeren Bech, of e-mail security firm Tumbleweed Communications.
"Importantly it could be caused by little more than a single disgruntled former employee."