Boston ? Doug Mientkiewicz, call a lawyer. You’re going to need one if you want to keep the baseball you caught for the final out of the World Series.

The Red Sox first baseman is storing the ball that clinched Boston’s first title since 1918 in a safe-deposit box near his Florida home. But the Red Sox want it back so they can show it off, and legal scholars say the team has a good case if it wants to fight Mientkiewicz in court.

“What appears to be emerging as a legal consensus is that the person with the least rights to it is Mientkiewicz himself,” said Yale Law School Dean Harold Hongju Koh, who ranked the claims as: “the Cardinals, the Red Sox, Major League Baseball and then the guy who happened to hold it at the end of the game.”

Baseball clubs don’t routinely distribute game balls like football teams do, and the final out is most likely to wind up tossed to a fan unless one of the players reached a milestone that day. No one has spent much time discussing who actually owns the ball because, until now, it hasn’t really mattered.

As the rise of the memorabilia market makes such items increasingly valuable, though, baseball is being forced to confront the issue of who owns the otherwise interchangeable pieces — the bases, the balls, the uniforms — that make the game go. On the same day the Red Sox clinched the Series, the ball Barry Bonds hit for his 700th career homer sold for $804,129.

“What this has done is force the baseball teams and MLB to make some decisions about who gets the noncontractual value of a valuable trophy,” said Paul Finkelman, a law professor at the University of Tulsa. “Does he (Mientkiewicz) get a $500,000 bonus because he’s the last guy to hold it?”

Mientkiewicz happened upon his keepsake when St. Louis shortstop Edgar Renteria knocked it back to Red Sox pitcher Keith Foulke with two outs in the ninth inning of the fourth game of the World Series. Foulke made an underhand toss to first base, and Boston’s 86-year title drought was over.

Mientkiewicz also made the final putout of the AL championship series victory over the New York Yankees and gave that ball to pitcher Derek Lowe. But the first baseman kept this one, and it was among the many items authenticated by Major League Baseball in the chaotic clubhouse afterward.

Mientkiewicz initially called the ball his “retirement fund,” though he later backed off those comments and said he wants it for sentimental value. The problem is, so does the team that waited nine decades to even have a chance to talk about the last out of a World Series victory.

“It’s not Doug’s ball. It belongs to all of us,” said Roger Abrams, a Northeastern University law professor who has written several baseball books. “He is the trustee of the ball but it is owned by all of Red Sox Nation, and it should find a place of special importance, either at Fenway or Cooperstown.”

Finkelman, who was an expert witness in the court fight over Bonds’ 73rd home run ball, said the fact that Mientkiewicz was a midseason addition and a late-inning replacement makes his claim to the ball tenuous. If he had made a leaping catch to secure the victory, been a major contributor during the regular season or even weathered the franchise’s lean years, fans and courts might be more sympathetic.

“The notion that Mientkiewicz did anything is absurd. He didn’t do anything,” Finkelman said.