Anyone hosting a party where alcohol is being served could be left with more than a mess to clean up in the morning if they haven't planned ahead. Serving alcohol to someone may expose you to risks you weren't aware of. You are responsible for what happens to guests when they are in your home or on your property. You are also responsible for your guests at other functions you organize, like company parties. And you may be held responsible for the safety and behaviour of your guests until they're sober, not just until they leave your party or function.
Some people find it hard to say no.
Don't make it harder for them. Don't pour doubles. Don't rush refills. Make sure food is available. Food helps slow down the speed at which alcohol is absorbed into a person s bloodstream.