Under Massachusetts law, when a person is arrested on a 3rd offense (or some additional offense), the DA may request a dangerousness hearing, where he or she will attempt to convince the judge that the arrested driver is a danger to society and should not be released on bail prior to the trial or other resolution of the issue.  If the judge agrees, the driver is not going home. Of course, the driver still faces additional, significant penalties if convicted.   Here is a relevant portion of Massachusetts General Laws Chapter 90, Section 24, to give you some idea of the stiff penalties your friend may be facing:

If the defendant has been previously convicted or assigned to an alcohol or controlled substance education, treatment or rehabilitation program by a court of the commonwealth or any other jurisdiction because of a like offense four or more times preceding the date of the commission of the offense for which he has been convicted, the defendant shall be punished by a fine of not less than two thousand nor more than fifty thousand dollars and by imprisonment for not less than two and one-half years or by a fine of not less than two thousand nor more than fifty thousand dollars and by imprisonment in the state prison for not less than two and one-half years nor more than five years; provided, however, that the sentence imposed upon such person shall not be reduced to less than twenty-four months, nor suspended, nor shall any such person be eligible for probation, parole, or furlough or receive any deduction from his sentence for good conduct until he shall have served twenty-four months of such sentence(.)

It's good that your friend has a Massachusetts attorney, as most who do this type of defense work will tell you that, because of the stiff penalties involved, it is almost always in the defendant's interest to go to trial and force the Commonwealth to prove its case, AND that the prior conviction occurred.  This is often difficult to show with older convictions.  For more information visit our Massachusetts Criminal Law Discussion Forum.