The drinks brand said it is working with trading standards throughout the country to educate outlets and staff on consumer rights.
Passing off is the act of serving products that are different from those advertised or asked for by the customer, without notifying them.
Pouring over is serving consumers what they are led to believe is a genuine product, but is in fact an imitation, such as filling a genuine branded spirit bottle with an inferior product.
As the words "Jägermeister"; "Jäger"; "Jäger Bomb" and "J-Bomb" are trademarked across the EU, any product sold under these names must be genuine.
The firm said most licensed premises understand and abide by the law, but it is looking to tackle the “less than 1% of outlets” engaging in the practices.
But the Publican’s Morning Advertiser understands that in a recent pilot crackdown of venues targeted by the herbal liqueur brand, 90% were found to have passed off the drink.
Mast-Jaegermeister UK staff have since given verbal warnings to “any outlets that may be failing to abide by the law” and last month sent out ‘cease and desist’ letters to identify repeat offenders.
It said its preference is to engage with owners and managers to rectify the situation without the need to resort to legal action, but outlets found offending repeatedly “will be followed up with appropriate action”.
Maximum penalties are a £20,000 fine or prison sentence, while the licence to sell alcohol can also be suspended or revoked.
Last August, the then owners of New York, New York in Norwich were fined in excess of £16,000 after being found guilty of deceiving the public and misusing trademarks, in a case brought by the drinks brand and trading standards.
Mast-Jaegermeister UK CEO Guy Lawrence said: “We’re not after the illinformed. But outlets that wilfully flout the law should know we intend to stay on their case. A small but persistent minority are undermining the trust of the consumer in all of us. It impacts manufacturers and damages consumer confidence in the trade. People need to realise that the penalties applied for passing off and pouring over can be severe."
Simon Green, marketing director of Global Brands, which produces Jungfrau, said: “With the herbal liqueurs category flourishing at a challenging time for the industry, it is surprising to see a brand owner threatening the trade for ‘passing off’. The category is not a one brand solution, with a number of brands standing as legitimate competitors. Not one of these competitor brands would want to be confused with Jagermeister and there is enough opportunity for all to co-exist without the need for aggressive legal action.”