Garrett Reid, 24, of Villanova, pleaded guilty to recklessly endangering another motorist, driving while under the influence, possession of drug paraphernalia and minor traffic offenses.
Reid ran a red light on Jan. 30 in Plymouth Township and hit another car. Police said he admitted to having used heroin earlier in the day, and they reportedly found syringes and drug paraphernalia on him, as well as a variety of pills in his vehicle.
Reid said Thursday he was sorry for causing the accident and injuring the other driver.
He said he would "stand up right now and take the consequences that have been given to me and that I deserve."
The DUI charge carries a minimum of 72 hours in jail and a maximum of 30 days.
"If you commit this crime, you're doing 72 hours, no matter who you are," said senior Deputy Attorney General Marc Costanzo, the prosecutor for both cases.
In the same Montgomery County courtroom on Thursday, 22-year-old Britt Reid requested a jury trial on charges stemming from a traffic dispute in which police said he brandished a handgun at another motorist. That alleged incident also occurred Jan. 30, in the Philadelphia suburb of West Conshohocken.
Britt Reid faces charges of carrying a firearm without a license - a felony - and misdemeanor charges of assault, making terroristic threats and drug possession.
Britt Reid's trial is set for mid-August.
His lawyers said they would continue to discuss a plea deal with prosecutors but are prepared to go to trial if no agreement is reached.
"We have two weeks to see how that case will turn out," said Ross Weiss, an attorney representing both brothers.
Garrett Reid will be sentenced following a drug and alcohol evaluation. Prosecutors will make no recommendation for sentencing as part of the arrangement.
Garrett Reid spent two months in a Florida drug treatment facility following the accident and speaks with a counselor there by phone at least once a week, he told the court.
Costanzo said Garrett Reid was not eligible for a program for first-time offenders because of a previous arrest.
The state Attorney General's office prosecuted both cases because of a possible conflict of interest involving the county district attorney's office.
Following the arrests, Andy Reid took a five-week leave of absence to be with his family but returned to the team in March. He did not attend Thursday's proceedings.