The Intoxicating Liquor Act 2003 that the Government is hoping will tackle growing alcohol-related problems takes effect today.
The legislation imposes tougher penalties on both drinkers and licensees relating to the over-consumption of alcohol.
Publicans will be breaking the law if they allow drunkenness on, or outside, their premises, and drunk people refusing to follow the instructions of policewill be liable to big fines.
"Happy hour" promotions are prohibited under the new legislation, and entertainment during the 30 minutes "drinking-up" time, is to be banned.
Licensees who sell alcohol to a drunken person or allow drunkenness on their premises will face fines of more than €1,500 for a first offence and €2,000 for a second or subsequent one.
The act also declares: "A person who is drunk on leaving licensed premises is presumed, until the contrary is proved, to have been drunk while on thosepremises", a clause questioned strongly by the Irish Council for Civil Liberties.
Mr Malachy Murphy, co-chair of the Council, said this area of the legislation is in direct contrast to standard civil liberties that deem all persons "innocent until proven guilty.
"Here the onus is being put on the accused person to prove that they are not drunk," said Mr Murphy.
Mr Murphy states that drinkers will be presented with a Catch 22-type situation, if and when they decide that they have had enough to drink, because staying on the premises while drunk is now illegal, as is leaving.
Concern is also expressed by Mr Murphy over what he describes as the "subjective" laws governing whether a person is or is not drunk.Unlike the testing of suspected drunk drivers there is no scientific measures to prove a person's drunkenness and it is therefore feared that the law may be abused.
However, a spokesperson for the Vintners' Federation of Ireland said that the body "broadly welcomed the act" as it has been lobbying for measures such as the introduction of a national idenfication card for 17 years.
According to the Minister for Justice, Mr Michael McDowell, the new law has demonstrated the determination of the Government to address the public order and public health worries arising from excessive drinking.
Plain-clothed police will also get extra powers under the provisions coming into effect today, and temporary closure orders will also be made available to punishpubs allowing drunkenness or disorderly conduct.
Drinkers who ignore police will be subject to a €300 fine for a first offence and €500 for a second or subsequent one.
The provisions also amend the current law, allowing licensees to set a minimum age for the sale and consumption of alcohol over the statutory minimum of 18years.
PA