Legal Question in Landlord & Tenant Law in Massachusetts

First, you need to review the terms of the lease which you signed. If the lease states you have a right to make or change rules from time to time, you can make a limited number of restrictions such as the consumption of alcohol other than in the back yard is prohibited and some reasonable restrictions on noise.

You cannot prohibit the consumption of alcohol outside altogether. You can keep it away from your neighbors and require other restricitons.

You can also send a 30 day notice to quit, which if they are month to month tenant is your privilidge. They may fight eviction. Another way is to ask for a new lease with an increase in rent and restrictions on consumption of alcohol in public areas, but you can't prohibit it altogether.

Good Luck

If I were you, I would send them a letter stating your preference that they do not drink alcohol in the front yard and driveway area. If you are simply dissatisfied with them as tenants, you have the right to evict them simply by giving them 30 day's notice via a legally sufficient Notice to Quit. You should retain counsel to accomplish this, as one minor mistake in the process can jeopardize the entire eviction.