An animal rights activist whose long-running campaigns made him notorious in hunting circles has won a landmark ruling that his anti-hunting beliefs should be protected from discrimination in the same way as religion.

Since the age of 15, Joe Hashman has taken part in non-violent direct action, sometimes acting outside the law, and undercover investigations against those involved in fox and hare hunting. His activities included covert filming which helped convict TV chef Clarissa Dickson-Wright in 2009 of attending hare-coursing, and have put him at odds with many in his community. At one point, he wrote a gardening column under a pseudonym because he feared the local paper would not allow him the space under his real name.

Hashman, 42, now a professional gardener, claims he was sacked from his job as a designer at Orchard Park Garden Centre in Dorset, when his bosses realised he was a hunt saboteur.

In a decision which is expected to pave the way for animal rights activists nationwide, a judge ruled his animal rights beliefs were a "philosophical belief" akin to religion under employment law.

He alleges he was sacked in September 2009. Hashman, of Dorset, took his employers, Ron and Shelia Clarke, members of the South and West Wiltshire Hunt, to a tribunal seeking damages. He claims that it was the third time he has been sacked for his beliefs.

Judge Lawrence Guyer ruled that Hashman's belief in the sanctity of life "extends to his fervent anti-fox hunting belief " and such beliefs should be protected under 2003 employment regulations.

Hashman, a father of two, said that his previous role as an active anti-hunt campaigner, which he has now given up, has "followed me about".

He said: "Trying to articulate my life's work and actions as a hunt saboteur and advocate for animals has not been easy. At times I have felt exposed and vulnerable. But ultimately I feel vindicated and am proud to have pursued this action."

Lawyers for his employers argued that Hashman's beliefs were "incoherent, inconsistent, politically motivated by class war and that they endorsed violence" so were not worthy of respect. They cited evidence from various literature ranging from the Hunt Saboteurs Association to the former Prime Minister, Tony Blair's autobiography, in which he said the fox hunting ban caused "inordinate political convulsions" to argue that it was a class-riven issue.

The judge rejected the argument and said that Hashman's beliefs about fox-hunting and hare coursing fell within the parameters of his general beliefs. Quoting Hashman, he held that he believes that "people should live their lives with mindful respect for animals and we all have a moral obligation to live in a way which is kind to each other, our environment and our fellow creatures."

Hashman was cross-examined for two hours, in which he was asked about his attitude to slicing worms in half – "he drew a distinction between vertebrates and other animals" – and about the most humane way to rid a garden of large white butterfly caterpillars, which was, according to an article he had written under the Dirty Nails , to "rub the little fellows out between his thumb and fingers".

Having established that Hashman holds a philosophical belief under the regulations, the case will now proceed to a hearing on unfair dismissal against him.

His solicitor, Shah Qureshi, of Bindmans, said: "The judgement is based on fact and a clear interpretation of the law rather than negative stereotype. It sends a clear signal that employers cannot discriminated against people merely because they disagree with their deeply held beliefs."

The judgment follows a similar ruling in November 2009. Then, a judge ruled that climate change campaigner Tim Nicolson's beliefs were so deeply held they were entitled to the same protection as religious beliefs under employment law.

Hashman was taken on by the Orchard park Garden Centre in Gillingham, Dorset, in March 2009, to work on garden design. On 2 September, the day of Dickson-Wright's conviction for hare coursing, he was advised by the garden centre manager, Richard Cumming that he should not attend the centre, due to a number of issues that had been "thrown up".

He alleges that, during a subsequent telephone conversation with Cumming, it was confirmed that his contract had been terminated because the Clarkes and a board member, Ludinda Stokes, who was a joint master of the hunt, were unhappy that he was working at Orchard Park because he was an animal rights activist and hunt saboteur.

Tensions were high, alleges Hashman, because of the conviction of Dickson-Wright and because of the death in August 2009 of Andrew Prater, the Clarkes's former farm manager and a prominent huntsman with whom Hashman, in his previous activities as a saboteur, had had several run-ins in the past.