BOSTON — Attorney General Maura Healey on Wednesday certified 21 proposed ballot questions submitted to her office for legal review, clearing the way for sponsors to proceed with signature gathering. Seven other initiatives were disqualified, including one that sought to eliminate tolls paid by motorists.

The attorney general certified proposals to gradually increase the state’s minimum wage to $15 per hour and another that would require employers to offer paid family leave and medical leave to workers. Measures that would lower the state’s 6.25 percent sales tax and require that future presidential candidates make their tax returns public before the election were also given the go-ahead by Healey.

Healey ruled that the proposal to eliminate tolls would violate a prohibition on the “uncompensated taking of property,” since tolls are used as security for bonds that are issued by the Massachusetts Department of Transportation.

Certification is only one step on a long road for sponsors of initiative petitions. They now face the task of collecting at least 64,750 signatures from registered voters by Dec. 6.

If that hurdle is crossed and the Legislature doesn’t act on the petition by next May, sponsors would then need to collect another 10,792 signatures to win a spot on the November 2018 ballot.

Only a handful of proposed questions typically reach the ballot in each election cycle.

State law requires that the attorney general’s review of the initiative petitions be limited to whether they met the legal criteria for ballot questions. Her office said the rulings were not influenced by personal views on the underlying issues.

Proposals can be disqualified on a number of grounds, including if they were improperly drafted, deal with an off-limits subject such as religion, freedom of speech or other constitutional rights, or call for a specific appropriation of state funds.

Steve Tougas, a Quincy resident who sponsored the petition on tolling, said he had expected it to be disqualified based on a previous ruling by the state’s highest court that he became aware of after the measure was filed.

He said many motorists were angered when the state broke a promise to eliminate tolls after the initial bonds that financed construction of the Massachusetts Turnpike were paid off, and others worried that tolling might be expanded to other highways including Interstate 93.

Healey, a Democrat, approved all four versions of a proposal by the Retailers Association of Massachusetts that would lower the sales tax to 4.5 or 5 percent and require the state to designate one tax-free weekend each summer. The group, which says it has been hurt by competitions from online retailers, plans to settle on one version to pursue with voters.