If you are pulled over at a DUI checkpoint in Massachusetts, it is important to remain calm and follow the instructions of the law enforcement officers. Here are some steps to consider:

1. Cooperate with the officers: Provide your driver's license, vehicle registration, and proof of insurance when requested. It is important to be polite and respectful throughout the interaction.
2. Know your rights: In Massachusetts, you have the right to remain silent. You do not have to answer any questions beyond providing your identification and vehicle documents. It is advisable to politely decline answering any further questions without the presence of an attorney.
3. Field Sobriety Tests (FSTs): In Massachusetts, you are not legally required to perform field sobriety tests, such as walking in a straight line or standing on one leg. These tests are subjective and can potentially be used against you. It is within your rights to politely refuse these tests.
4. Chemical Tests: Massachusetts has an implied consent law, which means that by driving on the state's roads, you have implicitly consented to chemical tests if suspected of DUI. Refusing a chemical test can result in immediate license suspension. However, it is advisable to consult with an attorney before making a decision.
5. Legal representation: If you are arrested or charged with DUI, it is crucial to seek legal representation as soon as possible. An experienced DUI attorney can guide you through the legal process, protect your rights, and help build a strong defense.

It is important to note that this information is provided as general guidance and should not be considered legal advice. Laws can vary, and it is advisable to consult with a qualified attorney for personalized assistance.

For more information, you can refer to the Massachusetts General Laws Chapter 90 Section 24 and consult with a legal professional.