A federal judge ruled today that Sharon McDonald can continue her civil-rights lawsuit against a Boston Police detective who had her arrested for a May, 2012 armed robbery in Roslindale, which led to her being locked up in a Suffolk County jail for eight days because she could not make the initial $5,000 bail.

The Suffolk County District Attorney's office dropped the charges against her after Det. Richard Walker realized she had a different height and accent than the ones described by the owner of the car the women allegedly used - who, it turned out, had a long criminal record, unlike McDonald, who had no record at all. Earlier in the investigation, clerks at the Madd Rags shop on American Legion Highway had failed to pick McDonald out of a photo array.

In a ruling today, US District Court Magistrate Judge Judith Gail Dein ruled against some of McDonald's claims - for example, her allegation of "intentional infliction of emotional distress" - but denied Walker's request to drop McDonald's charge that her civil rights had been violated.

Walker argued he was protected by "qualified immunity," which bars legal action against police officers when they make a well intentioned mistake.

Dein wrote that went out the window after she determined Walker's mistake was not well intentioned, because he never had valid probable cause to have McDonald arrested, and so violated her Fourth Amendment right against "unreasonable seizure."

Dein wrote that Walker tracked the registration number of the car the women used to a man named Fitzroy Swift - and that his first mistake was in believing Swift that he didn't actually own the car but had only registered it for a woman named Sharon McDonald, a 5'3" woman with a Jamaican accent living in Brockton - where, using RMV records, Walker found a woman with that name.

As an initial matter, Det. Walker did not act on any information derived from a verified, credible source. The initial piece of information that led Det. Walker to the plaintiff came from a phone conversation with the purported owner of the car that was used in the armed robbery. The owner of the car had a long criminal history, which included armed robbery, and he refused to meet with Det. Walker. By contrast, the plaintiff had no criminal history at all. Yet, Det. Walker's initial identification of the plaintiff as a suspect was based entirely on this information from someone he didn't know, who refused to meet with him, and who, allegedly, was not even present at the crime scene. Furthermore, Swift's story that he registered the car for a friend for some unknown reason, and for whom he did not provide an address, is not an inherently credible story in and of itself. This random identification of someone with a common name did not constitute probable cause. Moreover, all of the credible facts which Det. Walker did have contradicted any conclusion that the plaintiff was the perpetrator of the armed robbery. For example, the victims of the crime did not identify the plaintiff from a photo array. Moreover, even assuming that Swift could be believed, he described someone who did not match the plaintiff's description on her license. The difference between a 5'3" woman and a 5'8" woman is a very significant difference. The surveillance tape which Det. Walker allegedly viewed before seeking the arrest warrant did not create probable cause. Det. Walker himself testified that the video was not a very good surveillance picture, and the clarity "wasn't definite." This court has reviewed the video in question, and the picture quality is so poor that it is hard to make out the individuals involved in the robbery, let alone specific physical features. In sum, considering the circumstances as a whole - the poor quality video, the suspect information from a seemingly unreliable source, and the facts which described someone other than the plaintiff - Det. Walker "has not shown that the facts and circumstances 'were sufficient to warrant a prudent man in believing that the petitioner had committed or was committing an offense.' " Daley v. Harber, 234 F. Supp. 2d 27, 31 (D. Mass. 2002) (quoting Vargas-Badillo v. Diaz-Torres, 114 F.3d 3, 6 (1st Cir. 1997)) (additional citations omitted). Based on the totality of the record, Det. Walker did not have probable cause to arrest the plaintiff as a matter of law.

Dein set an Oct. 24 hearing for the two sides to discuss setting a trial date.