The basic Car Insurance Requirements in Massachusetts are as follows:

Liability Insurance is a minimum requirement and a low cost car insurance option as long as the vehicle is not financed.

The liability Minimums are 20/40/5 (Bodily Injury and Property Damage)
20/40/5 Explained:

The first 20 represents $20,000, the maximum coverage for one person's injuries, $40,000 for the total coverage for all injuries sustained in one incident and last but not least $5,000 for the property damage maximum coverage amount.

Massachusetts Car Insurance Laws:
Insurance proof is a requirement at registration and of course after an accident. The First Offense penalty is up to $5,000 fine; up to one year in jail.