DOVER — The Delaware House of Representatives passed legislation Tuesday that would decriminalize small amounts of marijuana. Legislators voted along party lines after about 90 minutes of debate, with the bill passing 24 to 14. Two lawmakers abstained, and one was absent.

Not one Republican opted to support the proposal, although the Democratic majority was able to move the legislation through without minority support. The bill now heads to the Senate.

House Bill 39 would replace the criminal penalties for possession of marijuana with a civil penalty — a $100 fine. The bill initially did not differentiate between juveniles and adults, but an amendment introduced Tuesday would make that change, along with several others.

Filed by main sponsor Rep. Helene Keeley, D-Wilmington, the amendment would treat those over age 21 differently from young individuals. For people younger than 18, possession would remain a criminal offense. For those between ages 18 and 21, possession would be a civil violation on the first offense.

Any subsequent offenses would be an unclassified criminal misdemeanor, with the offender subject to a fine of $100. One criminal conviction could be expunged when a person turns 21.

For those over 21, nothing regarding possession would change.

Using cannabis in a moving car would be a criminal penalty under the amendment, which defines marijuana solely as the “dried leaves and flowering tops of the plant cannabis sativa L.”

Under the purview of House Bill 39, anyone caught with more than 1 ounce of marijuana would face prison time of three months and a fine of $575.

Public use of up to one ounce would result in an unclassified misdemeanor, with a $200 fine and five days in prison.

The amendment clarifies the definition of public places, referring to them as sidewalks, parking lots, parks or “other areas to which the general public is invited,” as well as an outdoor location within 10 feet of a public place or a door or window that opens into a public or private building. The language means that, in essence, someone smoking marijuana in a backyard 9 feet from the entrance to “any public or private building” would face up to five days in prison if caught by police, while someone just a foot farther back would be penalized only by a fine of $100.

The bill sponsors come solely from the Democratic Party, and on Tuesday, only Democrats voted yes. The amendment seemed for a time like it would do more harm than good, with several co-sponsors expressing concerns the new form of the bill was unfair to minors.

“If both sides don’t like the bill, it’s usually a good bill,” said Rep. James Johnson, D-New Castle. “But it’s also been my experience, during compromise, that people that did not support the legislation even though you compromised with them, they’re not going to support anyway. And sometimes they use amendments, and they’re supposed to support, to sabotage your legislation. And the people that were supporting you from the beginning kind of lose faith in it.”

Despite his misgivings over the changes, he did vote for the bill because “the minority community through history has suffered the worst” from the war on drugs, he said.

Rep. Johnson was not the only lawmaker concerned with the amendment — even the sponsor said she felt more concessions were made than she wanted.

The amendment would treat cannabis use the same for those under 18 as it does for alcohol, although older individuals would face more severe punishments. The “fragmented” penalties also drew criticism from Rep. Michael Ramone, R-Pike Creek Valley, who referred to the punishments as inconsistent.

Although several lawmakers have said they are in favor of full legalization, Rep. Keeley stressed throughout the discussion she does not view this legislation as a stepping stone.

“The goal of the bill is not, I repeat, not legalization,” she said.

But while she may feel decriminalization would benefit myriad Delawareans, others made clear they think it goes too far and raises far more questions than it solved.

“Are we doing young people a favor by taking away this disincentive for behavior that is destructive to themselves and to their families?” Rep. Rich Collins, R-Millsboro, said. “If we pass this bill today, tomorrow the young people of Delaware, even though I know the amendment strengthened it a little bit, they’re going to get the clear message that the state of Delaware says, marijuana is ok. I do not see how that could not possibly lead to more demand, more illegal drug selling and other opportunities to sell other drugs to those same folks.”

Rep. Stephen Smyk, R-Milton, has been perhaps the strongest opponent of decriminalization. A former police officer, he noted in the committee hearing there is no specific law against buying marijuana, something echoed by Rep. Joseph Miro, R-Pike Creek Valley, on the House floor.

Police have argued against the bill, stating it would potentially hinder their ability to perform searches and could lead to more drug dealers.

According to a March poll by Public Policy Polling, 68 percent of respondents supported changing the penalty for possession from up to six months in prison to a $100 fine. According to the Delaware Criminal Justice Council, more than 2,300 people were arrested for marijuana possession in 2013, although only a small handful were incarcerated.

Gov. Jack Markell, a Democrat, has come out in favor of decriminalization.

The bill now heads to the Senate, which is also controlled by Democrats.