KGW-TV, Portland, Ore.

SHERWOOD, Ore. — An Oregon family is expressing frustration through social media at what they say is abuse of their 1-year-old child at the hands of the child's babysitter.

In an extensive post to Facebook last week, Joshua Marbury, of Sherwood, Ore., shared pictures of his son, Jacob, that showed bruises on the child's face.

According to the parents, the abuse happened in March when they were out on a date. When they returned home after being away for two hours, they found their babysitter asleep on a couch and Jacob crying. In the morning, they noticed the boy had a black eye, as well as bruising and scratches on his face.

Marbury said that an Oregon court ruling is blocking the alleged abuser, the child's babysitter, from facing criminal charges.

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"I've waited patiently for three months," said Jacob's mother, Alicia Quinney, "and I've been told they were going over all the medical records. ... And now two days ago, I was told they can't because of this law."

According to court language, in order to prove felony abuse of a child, prosecutors must show that the child had "substantial pain" and incurred a "physical injury." An obstacle can arise for children who are too young to explain their injuries or even describe what happened, as would be the case with a 1-year-old.

In this case, because the child had bruises and not something as apparent as an open gash, it makes a felony abuse charge harder to prove, legal officials said.

Jacob's parents are lobbying to get the law changed to provide additional protection to young victims and those whose disabilities make it difficult for them to speak. The alleged abuser in their child's case has not been charged with a crime.

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"That bruising says enough," Quinney said. "It was so bad, it was everywhere."

The babysitter was Marbury's best friend of 10 years. Quinney said the babysitter finally admitted to police he hit Jacob, but because Jacob is too young to talk and describe his pain level, prosecutors wouldn't be to convict on the highest penalty — felony assault. Just having bruises doesn't qualify for a felony in Oregon, either.

Professor Tung Yin of Lewis and Clark Law School said the Oregon law is pretty standard and balanced so the burden of proof is on the prosecution.

"We have to make a sort of choice here," he said. "The easier we make it to convict somebody, then the more we will avoid the sorts of cases that seem like they're injustices. But at the same time, we'll make it more likely there will be more people who will be wrongly convicted."

The Washington County District Attorney's office said it is still evaluating the case. It said "they continue to evaluate the case based on the Oregon Court of Appeals ruling." It could still bring misdemeanor child abuse charges.

"A misdemeanor is not enough," Quinney said. "He admitted to abusing a child. This guy is a big, huge guy. No matter who it is, no one should be able to abuse a child."

A Change.org petition seeking "justice for child abuse victims" had more than 26,000 signatures Tuesday. The petition is directed at Oregon's Supreme Court justices.

Contributing: Nina Mehlhaf, KGW-TV, Portland, Ore. Follow KGW on Twitter: @KGWNews