Allegations of alcohol abuse are often advanced to restrict a parent's access to his/her children in both child custody cases and in child welfare (children's aid society) cases. There are reliable measures available to challenge such allegations.
Yes, it does cost money. But the money spent on remote alcohol monitoring is a lot cheaper than extensive lawyers' fees. One such company that will affix a device to your body to remotely measure alcohol consumption is Recovery Science Corporation. The founder of this company is a lawyer.
Another company is Viaguard Accu-Metrics in Toronto. This company uses iPhone 5 technology platform to capture alcohol levels from remote locations. The device's camera captures your picture as you blow into the device. The device transmits your reading to a secure server. A report can be instantly transferred as directed by the court order, for example to the other parent.
Where alcohol consumption is an issue in your case, it is well worth contacting these companies to see if their testing mechanisms would be appropriate for your case. Such remote testing should be accompanied with an appropriate court order.