THE SUPREME Court on Wednesday overturned yet another federal law meant to check corruption and influence-peddling in national politics. The ruling shows two things: The Roberts Court’s destructive view on these matters wasn’t changed by the backlash to its Citizens United holding, and Congress must respond by designing new rules that can pass the court’s overly skeptical review. If lawmakers tackle the issue forthrightly, they have some workable options.

The court eliminated an overall limit on how much donors could give to candidates, parties and various other committees over the course of an election cycle. The idea had been to make it harder for big donors to circumvent limits on direct donations to candidates by siphoning them through other channels, or for political leaders to ask for large checks from wealthy individuals.

In the plurality opinion in McCutcheon v. Federal Election Commission, Chief Justice John G. Roberts Jr. held that the overall donation ceiling is an unconstitutional infringement on free speech because the government can regulate political giving only in order to prevent “quid pro quo corruption,” which is something like direct bribery. The chief justice insisted that combating the purchase of political influence and access is not a sufficiently worthwhile goal. Elsewhere, and without really owning up to it, he overturned a previous court holding in Buckley v. Valeo , the controlling precedent on the constitutionality of campaign finance limits. So much for the judicial restraint that Justice Roberts once promised.

That sort of purposeful judicial behavior worries us more than the practical results of its application in this ruling. Before Wednesday, the country already had to conduct its political affairs in a system damaged by Roberts Court decisions and by the holes in the campaign-finance system that predated it. Individuals, corporations and unions could spend vast amounts of money to manipulate federal elections, sometimes secretly, under fig-leaf restrictions that hardly reduce the potential for corruption or the appearance of it.

Congress cannot just leave it at that. Justice Roberts himself suggested that a variety of options can tighten up the system he is in part responsible for loosening, such as limiting cash transfers between committees and candidates. Lawmakers might also restrict candidates and other party leaders from soliciting large checks from big donors. There are ideas circulating for innovative public campaign-financing systems that could reduce the sway of wealthy individuals.

There is one particularly productive response to the Roberts Court that lawmakers should be able to enact immediately: requiring more prompt reporting about where political cash is coming from and where it is going. Americans would be able to evaluate the interests behind the candidates competing for their votes, and members of the court have repeatedly said that new transparency rules would promote accountability and fight corruption without impermissibly infringing on free speech.

Too bad, then, that Republicans have lately opposed this common-sense reform. We say lately because politicians such as Senate Minority Leader Mitch McConnell (R-Ky.) favored enhancing federal transparency rules until a Democrat-backed bill came before the Senate in 2012. They should not have filibustered then, and they should reconsider when the matter comes up again.