During a 19 year career in the Maryland Legislature, John Pica was the chief sponsor of many enacted laws. 

- Ban on Assault Weapons (1992) - landmark legislation banning 19 assault pistols, adding 23 assault rifles to the waiting period and providing mandatory sentences. The legislation became a national model for other states and the impetus for the U.S. Congress which passed a similar law just months after the Maryland Legislature enacted the ban. 

- Firearms, Access to Minors (1992) - prohibiting a person from storing or leaving a loaded firearm within the reach or access of a minor. The legislation became a national model for other states. 

Welfare Reform Act (1995) - making Maryland one of the first states to pass welfare reform. The legislation was enacted prior to the federal welfare reform act. 

Hearsay Testimony in Child Abuse Cases (1998) - allowing children who are victims of child abuse to testify by closed circuit television eliminating the anxiety and fear young children experience testifying in front of their abusers. This legislation is the national model for child abuse cases. Today, all 50 states have such a law. 

Suspension of Driver's License for Failure to Pay Child Support (1995) - automatic suspension of drivers' licenses for spouses who fail to pay child support. Maryland was one of the first states to pass this law. The legislation became a national model for other states. 

Abatement of Nuisances (1991)allowing a community association to evict a tenant who is distributing or storing drugs on their premises. Maryland was the first state to pass such a law. The legislation become a national model for other states. 

- Disparity Grant (1992) arguably the most important legislation to pass for the poorer jurisdictions in Maryland. The law redistributes revenue from income taxes based on a formula which directs the additional money to the poorer counties and Baltimore City. Baltimore City alone received an additional sum of $35 million in 1994, saving hundreds of jobs and programs in Baltimore City, Allegany, Garrett, Somerset, and Wicomico counties. 

School Bus Fares (1992) allowing the City of Baltimore to use transportation money to pay for the students' cost of public school transportation. 

- Ban of Child Pornography on Computers (1988) prohibiting the commercial use, solicitation or sale of child pornography through the internet. Maryland was one of the first states the pass this legislation.